101
|
Goodwin NB, Dulvy NK, Reynolds JD. Macroecology of live-bearing in fishes: latitudinal and depth range comparisons with egg-laying relatives. OIKOS 2005. [DOI: 10.1111/j.0030-1299.2005.13859.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
102
|
Mora C, Robertson DR. CAUSES OF LATITUDINAL GRADIENTS IN SPECIES RICHNESS: A TEST WITH FISHES OF THE TROPICAL EASTERN PACIFIC. Ecology 2005. [DOI: 10.1890/04-0883] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
103
|
Hunt G, Cronin TM, Roy K. Species-energy relationship in the deep sea: a test using the Quaternary fossil record. Ecol Lett 2005. [DOI: 10.1111/j.1461-0248.2005.00778.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
104
|
McClain CR, Etter RJ. Mid-domain models as predictors of species diversity patterns: bathymetric diversity gradients in the deep sea. OIKOS 2005. [DOI: 10.1111/j.0030-1299.2005.13529.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
105
|
Bellwood DR, Hughes TP, Connolly SR, Tanner J. Environmental and geometric constraints on Indo-Pacific coral reef biodiversity. Ecol Lett 2005. [DOI: 10.1111/j.1461-0248.2005.00763.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
106
|
Portner HO. Climate variability and the energetic pathways of evolution: the origin of endothermy in mammals and birds. Physiol Biochem Zool 2005; 77:959-81. [PMID: 15674770 DOI: 10.1086/423742] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2004] [Indexed: 11/03/2022]
Abstract
Large-scale climate oscillations in earth's history have influenced the directions of evolution, last but not least, through mass extinction events. This analysis tries to identify some unifying forces behind the course of evolution that favored an increase in organismic complexity and performance, paralleled by an increase in energy turnover, and finally led to endothermy. The analysis builds on the recent concept of oxygen-limited thermal tolerance and on the hypothesis that unifying principles exist in the temperature-dependent biochemical design of the eukaryotic cell in animals. The comparison of extant water-breathing and air-breathing animal species from various climates provides a cause-and-effect understanding of the trade-offs and constraints in thermal adaptation and their energetic consequences. It is hypothesized that the high costs of functional adaptation to fluctuating temperatures, especially in the cold (cold eurythermy), cause an increase in energy turnover and, at the same time, mobility and agility. These costs are associated with elevated mitochondrial capacities at minimized levels of activation enthalpies for proton leakage. Cold eurythermy is seen as a precondition for the survival of evolutionary crises elicited by repeated cooling events during extreme climate fluctuations. The costs of cold eurythermy appear as the single most important reason why metazoan evolution led to life forms with high energy turnover. They also explain why dinosaurs were able to live in subpolar climates. Finally, they give insight into the pathways, benefits, and trade-offs involved in the evolution of constant, elevated body temperature maintained by endothermy. Eurythermy, which encompasses cold tolerance, is thus hypothesized to be the "missing link" between ectothermy and endothermy. Body temperatures between 32 degrees and 42 degrees C in mammals and birds then result from trade-offs between the limiting capacities of ventilation and circulation and the evolutionary trend to maximize performance at the warm end of the thermal tolerance window.
Collapse
Affiliation(s)
- Hans O Portner
- Alfred-Wegener-Institut fur Polar-und Meeresforschung, Okophysiologie, Postfach 12 01 61, D-27515 Bremerhaven, Germany.
| |
Collapse
|
107
|
Parmesan C, Gaines S, Gonzalez L, Kaufman DM, Kingsolver J, Townsend Peterson A, Sagarin R. Empirical perspectives on species borders: from traditional biogeography to global change. OIKOS 2005. [DOI: 10.1111/j.0030-1299.2005.13150.x] [Citation(s) in RCA: 265] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
108
|
Davies TJ, Savolainen V, Chase MW, Moat J, Barraclough TG. Environmental energy and evolutionary rates in flowering plants. Proc Biol Sci 2004; 271:2195-200. [PMID: 15475341 PMCID: PMC1691837 DOI: 10.1098/rspb.2004.2849] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The latitudinal gradient in species richness is a pervasive feature of the living world, but its underlying causes remain unclear. We evaluated the hypothesis that environmental energy drives evolutionary rates and thereby diversification in flowering plants. We estimated energy levels across angiosperm family distributions in terms of evapotranspiration, temperature and UV radiation taken from satellite and climate databases. Using the most comprehensive DNA-based phylogenetic tree for angiosperms to date, analysis of 86 sister-family comparisons shows that molecular evolutionary rates have indeed been faster in high-energy regions, but that this is not an intermediate step between energy and diversity. Energy has strong, but independent effects on both species richness and molecular evolutionary rates.
Collapse
Affiliation(s)
- T Jonathan Davies
- Department of Biological Scienes and NERC Centre for Population Biology, Imperial College, London. Ascot SL7 7PUY, UK
| | | | | | | | | |
Collapse
|
109
|
Pörtner HO, Mark FC, Bock C. Oxygen limited thermal tolerance in fish?--Answers obtained by nuclear magnetic resonance techniques. Respir Physiol Neurobiol 2004; 141:243-60. [PMID: 15288597 DOI: 10.1016/j.resp.2004.03.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/04/2004] [Indexed: 10/26/2022]
Abstract
In various phyla of marine invertebrates limited capacities of both ventilatory and circulatory performance were found to set the borders of the thermal tolerance window with limitations in aerobic scope and onset of hypoxia as a first line of sensitivity to both cold and warm temperature extremes. The hypothesis of oxygen limited thermal tolerance has recently been investigated in fish using a combination of non-invasive nuclear magnetic resonance (NMR) methodology with invasive techniques. In contrast to observations in marine invertebrates arterial oxygen tensions in fish were independent of temperature, while venous oxygen tensions displayed a thermal optimum. As the fish heart relies on venous oxygen supply, limited cardio-circulatory capacity is concluded to set the first level of thermal intolerance in fish. Nonetheless, maximized ventilatory capacity is seen to support circulation in maintaining the width of thermal tolerance windows. The interdependent setting of low and high tolerance limits is interpreted to result from trade-offs between optimized tissue functional capacity and baseline oxygen demand and energy turnover co-determined by the adjustment of mitochondrial densities and functional properties to a species-specific temperature range. At temperature extremes, systemic hypoxia will elicit metabolic depression, thereby widening the thermal window transiently sustained especially in those species preadapted to hypoxic environments.
Collapse
Affiliation(s)
- H O Pörtner
- Alfred-Wegener-Institut für Polar- und Meeresforschung, Okophysiologie, Postfach 12 01 61, D-27515 Bremerhaven, FRG, Germany.
| | | | | |
Collapse
|
110
|
Witman JD, Etter RJ, Smith F. The relationship between regional and local species diversity in marine benthic communities: a global perspective. Proc Natl Acad Sci U S A 2004; 101:15664-9. [PMID: 15501917 PMCID: PMC524210 DOI: 10.1073/pnas.0404300101] [Citation(s) in RCA: 224] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The number of species coexisting in ecological communities must be a consequence of processes operating on both local and regional scales. Although a great deal of experimental work has been devoted to local causes of diversity, little is known about the effects of regional processes on local diversity and how they contribute to global diversity patterns in marine systems. We tested the effects of latitude and the richness of the regional species pool on the species richness of local epifaunal invertebrate communities by sampling the diversity of local sites in 12 independent biogeographic regions from 62 degrees S to 63 degrees N latitude. Both regional and local species richness displayed significant unimodal patterns with latitude, peaking at low latitudes and decreasing toward high latitudes. The latitudinal diversity gradient was represented at the scale of local sites because local species richness was positively and linearly related to regional species richness. The richness of the regional species pool explained 73-76% of local species richness. On a global scale, the extent of regional influence on local species richness was nonrandom-the proportion of regional biota represented in local epifaunal communities increased significantly from low to high latitudes. The strong effect of the regional species pool implies that patterns of local diversity in temperate, tropical, and high-latitude marine benthic communities are influenced by processes operating on larger spatiotemporal scales than previously thought.
Collapse
Affiliation(s)
- Jon D Witman
- Ecology and Evolutionary Biology Department, Brown University, Providence, RI 02912, USA.
| | | | | |
Collapse
|
111
|
Bluhm BA, MacDonald IR, Debenham C, Iken K. Macro- and megabenthic communities in the high Arctic Canada Basin: initial findings. Polar Biol 2004. [DOI: 10.1007/s00300-004-0675-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
112
|
Abstract
Community ecology seeks to explain the number and relative abundance of coexisting species. Four research frontiers in community ecology are closely tied to research in systematics and taxonomy: the statistics of species richness estimators, global patterns of biodiversity, the influence of global climate change on community structure, and phylogenetic influences on community structure. The most pressing needs for taxonomic information in community ecology research are usable taxonomic keys, current nomenclature, species occurrence records and resolved phylogenies. These products can best be obtained from Internet-based phylogenetic and taxonomic resources, but the lack of trained professional systematists and taxonomists threatens this effort. Community ecologists will benefit most directly from research in systematics and taxonomy by making better use of resources in museums and herbaria, and by actively seeking training, information and collaborations with taxonomic specialists.
Collapse
Affiliation(s)
- Nicholas J Gotelli
- Department of Biology, University of Vermont, Burlington, VT 05405, USA.
| |
Collapse
|
113
|
Okuda T, Noda T, Yamamoto T, Ito N, Nakaoka M. Latitudinal gradient of species diversity: multi-scale variability in rocky intertidal sessile assemblages along the Northwestern Pacific coast. POPUL ECOL 2004. [DOI: 10.1007/s10144-004-0185-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
114
|
Guernier V, Hochberg ME, Guégan JF. Ecology drives the worldwide distribution of human diseases. PLoS Biol 2004; 2:e141. [PMID: 15208708 PMCID: PMC423130 DOI: 10.1371/journal.pbio.0020141] [Citation(s) in RCA: 378] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Accepted: 03/11/2004] [Indexed: 11/18/2022] Open
Abstract
Identifying the factors underlying the origin and maintenance of the latitudinal diversity gradient is a central problem in ecology, but no consensus has emerged on which processes might generate this broad pattern. Interestingly, the vast majority of studies exploring the gradient have focused on free-living organisms, ignoring parasitic and infectious disease (PID) species. Here, we address the influence of environmental factors on the biological diversity of human pathogens and their global spatial organization. Using generalized linear multivariate models and Monte Carlo simulations, we conducted a series of comparative analyses to test the hypothesis that human PIDs exhibit the same global patterns of distribution as other taxonomic groups. We found a significant negative relationship between latitude and PID species richness, and a nested spatial organization, i.e., the accumulation of PID species with latitude, over large spatial scales. Additionally, our results show that climatic factors are of primary importance in explaining the link between latitude and the spatial pattern of human pathogens. Based on our findings, we propose that the global latitudinal species diversity gradient might be generated in large part by biotic interactions, providing strong support for the idea that current estimates of species diversity are substantially underestimated. When parasites and pathogens are included, estimates of total species diversity may increase by more than an order of magnitude. Comparative analyses reveal that human pathogens increase towards the equator and that the relationship is linked to climate - this has important implications for global biodiversity, public health and environmental epidemiology
Collapse
Affiliation(s)
- Vanina Guernier
- Génétique et Evolution des Maladies Infectieuses, Montpellier, France.
| | | | | |
Collapse
|
115
|
Kaspari M, Ward PS, Yuan M. Energy gradients and the geographic distribution of local ant diversity. Oecologia 2004; 140:407-13. [PMID: 15179582 DOI: 10.1007/s00442-004-1607-2] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Accepted: 05/04/2004] [Indexed: 11/29/2022]
Abstract
Geographical diversity gradients, even among local communities, can ultimately arise from geographical differences in speciation and extinction rates. We evaluated three models--energy-speciation, energy-abundance, and area--that predict how geographic trends in net diversification rates generate trends in diversity. We sampled 96 litter ant communities from four provinces: Australia, Madagascar, North America, and South America. The energy-speciation hypothesis best predicted ant species richness by accurately predicting the slope of the temperature diversity curve, and accounting for most of the variation in diversity. The communities showed a strong latitudinal gradient in species richness as well as inter-province differences in diversity. The former vanished in the temperature-diversity residuals, suggesting that the latitudinal gradient arises primarily from higher diversification rates in the tropics. However, inter-province differences in diversity persisted in those residuals--South American communities remained more diverse than those in North America and Australia even after the effects of temperature were removed.
Collapse
Affiliation(s)
- Michael Kaspari
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA.
| | | | | |
Collapse
|
116
|
|
117
|
Hawkins BA, Field R, Cornell HV, Currie DJ, Guégan JF, Kaufman DM, Kerr JT, Mittelbach GG, Oberdorff T, O'Brien EM, Porter EE, Turner JRG. ENERGY, WATER, AND BROAD-SCALE GEOGRAPHIC PATTERNS OF SPECIES RICHNESS. Ecology 2003. [DOI: 10.1890/03-8006] [Citation(s) in RCA: 1632] [Impact Index Per Article: 77.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
118
|
Price RM. Columellar muscle of neogastropods: muscle attachment and the function of columellar folds. THE BIOLOGICAL BULLETIN 2003; 205:351-366. [PMID: 14672989 DOI: 10.2307/1543298] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Malacologists often assume that ornamentation on snail shells is functional, and therefore adaptive. I conducted the first comprehensive test of the widely accepted hypothesis that columellar folds, a type of internal ornamentation, enhance the performance of the columellar muscle, which attaches the snail to its shell. Careful dissections of live, non-relaxed specimens reveal that the physical attachment between the columellar muscle and the columella is not restricted to a small, circular patch located deep within the shell. Instead, the attachment is long and narrow, extending approximately a full whorl along the length of the columella. I developed a novel technique for preparing three-dimensional reconstructions from photographs documenting the dissections. These reconstructions were then used to measure four parameters that describe the muscle: (1) the surface area of the physical attachment between the muscle and columella, (2) the total contact area between the muscle and the columella, (3) the depth of attachment, and (4) the length of attachment. None of these parameters differed significantly between species with and without folds. In light of the biomechanics of muscular hydrostats, values of the first parameter indicate that columellar folds probably do not guide the columellar muscle as the animal moves in and out of its shell. Values of the other parameters indicate that columellar folds neither increase an animal's ability to maneuver its shell nor facilitate deeper withdrawal. These results, and the fact that folds have evolved convergently several times, might indicate that folds are an easily evolvable solution to many functional problems, none of which are currently understood.
Collapse
Affiliation(s)
- Rebecca M Price
- Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, Illinois 60637, USA.
| |
Collapse
|
119
|
Willig M, Kaufman D, Stevens R. Latitudinal Gradients of Biodiversity: Pattern, Process, Scale, and Synthesis. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2003. [DOI: 10.1146/annurev.ecolsys.34.012103.144032] [Citation(s) in RCA: 1393] [Impact Index Per Article: 66.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
▪ Abstract The latitudinal gradient of decreasing richness from tropical to extratropical areas is ecology's longest recognized pattern. Nonetheless, notable exceptions to the general pattern exist, and it is well recognized that patterns may be dependent on characteristics of spatial scale and taxonomic hierarchy. We conducted an extensive survey of the literature and provide a synthetic assessment of the degree to which variation in patterns (positive linear, negative linear, modal, or nonsignificant) is a consequence of characteristics of scale (extent or focus) or taxon. In addition, we considered latitudinal gradients with respect to generic and familial richness, as well as species evenness and diversity. We provide a classification of the over 30 hypotheses advanced to account for the latitudinal gradient, and we discuss seven hypotheses with most promise for advancing ecological, biogeographic, and evolutionary understanding. We conclude with a forward-looking synthesis and list of fertile areas for future research.
Collapse
Affiliation(s)
- M.R. Willig
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
- Division of Biology, Kansas State University, Manhattan, Kansas 66506-4901
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
| | - D.M. Kaufman
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
- Division of Biology, Kansas State University, Manhattan, Kansas 66506-4901
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
| | - R.D. Stevens
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
- Division of Biology, Kansas State University, Manhattan, Kansas 66506-4901
- Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
- National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
| |
Collapse
|
120
|
Zapata FA, Gaston KJ, Chown SL. Mid-domain models of species richness gradients: assumptions, methods and evidence. J Anim Ecol 2003; 72:677-690. [DOI: 10.1046/j.1365-2656.2003.00741.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
121
|
Astorga A, Fernández M, Boschi EE, Lagos N. Two oceans, two taxa and one mode of development: latitudinal diversity patterns of South American crabs and test for possible causal processes. Ecol Lett 2003. [DOI: 10.1046/j.1461-0248.2003.00445.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
122
|
Kaspari M, Yuan M, Alonso L. Spatial grain and the causes of regional diversity gradients in ants. Am Nat 2003; 161:459-77. [PMID: 12699224 DOI: 10.1086/367906] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Gradients of species richness (S; the number of species of a given taxon in a given area and time) are ubiquitous. A key goal in ecology is to understand whether and how the many processes that generate these gradients act at different spatial scales. Here we evaluate six hypotheses for diversity gradients with 49 New World ant communities, from tundra to rain forest. We contrast their performance at three spatial grains from S(plot), the average number of ant species nesting in a m2 plot, through Fisher's alpha, an index that treats our 30 1-m2 plots as subsamples of a locality's diversity. At the smallest grain, S(plot), was tightly correlated (r2 = 0.99) with colony abundance in a fashion indistinguishable from the packing of randomly selected individuals into a fixed space. As spatial grain increased, the coaction of two factors linked to high net rates of diversification--warm temperatures and large areas of uniform climate--accounted for 75% of the variation in Fisher's alpha. However, the mechanisms underlying these correlations (i.e., precisely how temperature and area shape the balance of speciation to extinction) remain elusive.
Collapse
Affiliation(s)
- Michael Kaspari
- Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
| | | | | |
Collapse
|
123
|
|
124
|
Hughes TP, Bellwood DR, Connolly SR. Biodiversity hotspots, centres of endemicity, and the conservation of coral reefs. Ecol Lett 2002. [DOI: 10.1046/j.1461-0248.2002.00383.x] [Citation(s) in RCA: 255] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
125
|
Abstract
Many organisms overlap in their use of resources in space and time. Where and when resources are restricted, species must compete for them. Living space, often a critical resource controlling food and mate availability, is directly contested by organisms in most habitats. The ensuing animal interactions generally result in a winner gaining space and a loser, which may die. Contact matrices from studies of interference competition in encrusting marine Bryozoa (clonal and colonial animals), spanning at least 60 degrees latitude in both hemispheres, were analysed and subjected to a modern transitivity index. Only data for Bryozoa were used because (i) use of a single taxon with restricted ecology simplifies the scope for types of encounters, (and therefore) interpretation; and (ii) ecological bias is reduced because bryozoans are abundant at all latitudes. The analysis shows that assemblage competition is more hierarchical towards both poles. Thus, poorer competitors fail more frequently in interactions with increasing latitude. The cause of this trend is the simplification of overall outcomes between competitors, such as fewer ties, reversals in outcome or competitive loops (where low-ranking competitors beat those of higher ranking). The implication of such a trend is that the maintenance of biological diversity at high latitudes may principally be by physical rather than biological (competition) processes. Certainly, ocean surface energy increases with latitude through wind and wave action (and ice scour in polar regions).
Collapse
Affiliation(s)
- David K A Barnes
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
| |
Collapse
|
126
|
Allen AP, Brown JH, Gillooly JF. Global biodiversity, biochemical kinetics, and the energetic-equivalence rule. Science 2002; 297:1545-8. [PMID: 12202828 DOI: 10.1126/science.1072380] [Citation(s) in RCA: 391] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The latitudinal gradient of increasing biodiversity from poles to equator is one of the most prominent but least understood features of life on Earth. Here we show that species diversity can be predicted from the biochemical kinetics of metabolism. We first demonstrate that the average energy flux of populations is temperature invariant. We then derive a model that quantitatively predicts how species diversity increases with environmental temperature. Predictions are supported by data for terrestrial, freshwater, and marine taxa along latitudinal and elevational gradients. These results establish a thermodynamic basis for the regulation of species diversity and the organization of ecological communities.
Collapse
Affiliation(s)
- Andrew P Allen
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
| | | | | |
Collapse
|
127
|
Abstract
The increase in species richness from the poles to the Equator has been observed in numerous terrestrial and aquatic taxa. A number of different hypotheses have been put forward as explanations for this trend, e.g. area and energy availability. However, whether these hypotheses apply to large spatial scales in marine environments remains unclear. The present study shows a clear latitudinal gradient from high to low latitude (from 80 degrees N to 70 degrees S) in marine species richness for 6643 species (fishes and invertebrates) in 10 different taxa dwelling in benthic and pelagic habitats on both sides of the Atlantic. The patterns in benthic taxa are strongly influenced by coastal hydrographic processes, with marked peaks and troughs, and consequently the gradients are not symmetric along both Atlantic sides. Pelagic taxa show a plateau-shaped distribution and the influence from coastal events on gradients could not be demonstrated. The relationships between species richness and different environmental factors indicate that area size does not explain the latitudinal pattern in benthic species richness on a large spatial scale. Sea-surface temperature (positive relationship) is the best predictor of this pattern for benthic species, and nitrate concentration (negative relationship) is the best predictor for pelagic species. The results call into question the existence of a single primary cause that would explain the pattern in marine species richness on a large spatial scale.
Collapse
Affiliation(s)
- E Macpherson
- Centro de Estudios Avanzados de Blanes (CSIC), Cami de Santa Barbara s/n, Girona, Spain.
| |
Collapse
|
128
|
Ellingsen K, Gray JS. Spatial patterns of benthic diversity: is there a latitudinal gradient along the Norwegian continental shelf? J Anim Ecol 2002. [DOI: 10.1046/j.1365-2656.2002.00606.x] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
129
|
Chown SL, Addo-Bediako A, Gaston KJ. Physiological variation in insects: large-scale patterns and their implications. Comp Biochem Physiol B Biochem Mol Biol 2002; 131:587-602. [PMID: 11923075 DOI: 10.1016/s1096-4959(02)00017-9] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper we demonstrate how broad scale comparative physiology has an important role to play in informing a variety of assumptions made in macroecology. We do so by examining large-scale geographic variation in insect development, thermal tolerance and metabolic rate. From these studies, and those from the literature on insect water loss and thermoregulation, we show that there is often a bias to the geographic extent of available empirical data. Studies of cold hardiness are most usually undertaken at high latitudes, while investigations of upper thermal tolerances and water loss are most common in warm arid regions. Likewise, we demonstrate that much variation in insect physiological tolerances is partitioned at higher taxonomic levels, which has important implications for comparative physiology. Intriguingly, data on the full range of variables we review are available for only three species. We also show that, despite its importance, body size is regularly reported in only some kinds of investigations (metabolic rate, water loss rate), whereas in others (upper lethal temperature, cold hardiness, development) this variable is often ignored. In short, although large-scale comparative physiology can contribute considerable understanding to both physiology and ecology, there is much that remains to be done.
Collapse
Affiliation(s)
- S L Chown
- Department of Zoology and Entomology, University of Pretoria, 0002, Pretoria, South Africa.
| | | | | |
Collapse
|
130
|
Clarke A, Lidgard S. Spatial patterns of diversity in the sea: bryozoan species richness in the North Atlantic. J Anim Ecol 2001; 69:799-814. [PMID: 29313988 DOI: 10.1046/j.1365-2656.2000.00440.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Andrew Clarke
- British Antarctic Survey, Cambridge CB3 0ET, UK; andField Museum of Natural History, Chicago, Illinois, USA
| | - Scott Lidgard
- British Antarctic Survey, Cambridge CB3 0ET, UK; andField Museum of Natural History, Chicago, Illinois, USA
| |
Collapse
|
131
|
|
132
|
Abstract
We discuss the general formation of complementary behaviors, functions and forms in biological species competing for resources. We call orthogonalization the related processes on macro and micro-level of a self-organized formation of correlations in the species properties. Orthogonalization processes could be, for example, easily observed in sympatric speciation, as we show in numerical studies carried out with a new population equation. As a practical result, we find that the number of species is proportional to the effective richness of resources and depends on their history.
Collapse
Affiliation(s)
- P Král
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
133
|
Gershwin LA. Systematics and biogeography of the jellyfish Aurelia labiata (Cnidaria: Scyphozoa). THE BIOLOGICAL BULLETIN 2001; 201:104-119. [PMID: 11526069 DOI: 10.2307/1543531] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The hypothesis that the common eastern North Pacific Aurelia is A. aurita is falsified with morphological analysis. The name Aurelia labiata is resurrected, and the species is redescribed, to refer to medusae differing from A. aurita by a suite of characters related to a broad and elongated manubrium. Specifically, the oral arms are short, separated by and arising from the base of the fleshy manubrium, and the planulae are brooded upon the manubrium itself, rather than on the oral arms. Aurelia aurita possesses no corresponding enlarged structure. Furthermore, the number of radial canals is typically much greater in A. labiata, and thus the canals often appear more anastomosed than in A. aurita. Finally, most A. labiata medusae possess a 16-scalloped bell margin, whereas the margin is 8-scalloped in most A. aurita. Separation of the two forms has previously been noted on the basis of allozyme and isozyme analyses and on the histology of the neuromuscular system. Partial 18S rDNA sequencing corroborates these findings. Three distinct morphotypes of A. labiata, corresponding to separate marine bioprovinces, have been identified among 17 populations from San Diego, California, to Prince William Sound, Alaska. The long-undisputed species A. limbata may be simply a color morph of A. labiata, or a species within a yet-unelaborated A. labiata species complex. The first known introduction of Aurelia cf. aurita into southern California waters is documented. Although traditional jellyfish taxonomy tends to recognize many species as cosmopolitan or nearly so, these results indicate that coastal species, such as A. labiata, may experience rapid divergence among isolated populations, and that the taxonomy of such species should therefore be scrutinized with special care.
Collapse
Affiliation(s)
- L A Gershwin
- Cabrillo Marine Aquarium, San Pedro, California 90731, USA.
| |
Collapse
|
134
|
Hellberg ME, Balch DP, Roy K. Climate-driven range expansion and morphological evolution in a marine gastropod. Science 2001; 292:1707-10. [PMID: 11387473 DOI: 10.1126/science.1060102] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Little is known about the phenotypic consequences of global climate change, despite the excellent Pleistocene fossil record of many taxa. We used morphological measurements from extant and Pleistocene populations of a marine gastropod (Acanthinucella spirata) in conjunction with mitochondrial DNA sequence variation from living populations to determine how populations responded phenotypically to Pleistocene climatic changes. Northern populations show little sequence variation as compared to southern populations, a pattern consistent with a recent northward range expansion. These recently recolonized northern populations also contain shell morphologies that are absent in extant southern populations and throughout the Pleistocene fossil record. Thus, contrary to traditional expectations that morphological evolution should occur largely within Pleistocene refugia, our data show that geographical range shifts in response to climatic change can lead to significant morphological evolution.
Collapse
Affiliation(s)
- M E Hellberg
- Department of Biological Sciences, 508 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | | |
Collapse
|
135
|
Smith AB. Large-scale heterogeneity of the fossil record: implications for Phanerozoic biodiversity studies. Philos Trans R Soc Lond B Biol Sci 2001; 356:351-67. [PMID: 11316484 PMCID: PMC1088432 DOI: 10.1098/rstb.2000.0768] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Patterns of origination, extinction and standing diversity through time have been inferred from tallies of taxa preserved in the fossil record. This approach assumes that sampling of the fossil record is effectively uniform over time. Although recent evidence suggests that our sampling of the available rock record has indeed been very thorough and effective, there is also overwhelming evidence that the rock record available for sampling is itself distorted by major systematic biases. Data on rock outcrop area compiled for post-Palaeozoic sediments from Western Europe at stage level are presented. These show a strongly cyclical pattern corresponding to first- and second-order sequence stratigraphical depositional cycles. Standing diversity increases over time and, at the coarsest scale, is decoupled from surface outcrop area. This increasing trend can therefore be considered a real pattern. Changes in standing diversity and origination rates over time-scales measured in tens of millions of years, however, are strongly correlated with surface outcrop area. Extinction peaks conform to a random-walk model, but larger peaks occur at just two positions with respect to second-order stratigraphical sequences, towards the culmination of stacked transgressive system tracts and close to system bases, precisely the positions where taxonomic last occurrences are predicted to cluster under a random distribution model. Many of the taxonomic patterns that have been described from the fossil record conform to a species-area effect. Whether this arises primarily from sampling bias, or from changing surface area of marine shelf seas through time and its effect on biodiversity, remains problematic.
Collapse
Affiliation(s)
- A B Smith
- Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
| |
Collapse
|
136
|
Roy K, Jablonski D, Martien KK. Invariant size-frequency distributions along a latitudinal gradient in marine bivalves. Proc Natl Acad Sci U S A 2000; 97:13150-5. [PMID: 11087865 PMCID: PMC27193 DOI: 10.1073/pnas.97.24.13150] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the most extensive analysis of body size in marine invertebrates to date, we show that the size-frequency distributions of northeastern Pacific bivalves at the provincial level are surprisingly invariant in modal and median size as well as size range, despite a 4-fold change in species richness from the tropics to the Arctic. The modal sizes and shapes of these size-frequency distributions are consistent with the predictions of an energetic model previously applied to terrestrial mammals and birds. However, analyses of the Miocene-Recent history of body sizes within 82 molluscan genera show little support for the expectation that the modal size is an evolutionary attractor over geological time.
Collapse
Affiliation(s)
- K Roy
- Section of Ecology, Behavior, and Evolution, Division of Biology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA.
| | | | | |
Collapse
|
137
|
Chown SL, Gaston KJ. Areas, cradles and museums: the latitudinal gradient in species richness. Trends Ecol Evol 2000; 15:311-315. [PMID: 10884694 DOI: 10.1016/s0169-5347(00)01910-8] [Citation(s) in RCA: 204] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although numerous factors are postulated to be responsible for the gradient of increasing taxon richness towards lower latitudes, it has recently been suggested that the primary determinant is geographic area. This area model is appealing in its logic, but there is little empirical evidence to support it and several other mechanisms might also interact to obscure its effects. Nonetheless, the model has highlighted several fundamental issues concerning range size, speciation and extinction that, despite their considerable significance, remain poorly understood.
Collapse
|
138
|
Gaylord B, Gaines SD. Competition and the Effect of Spatial Resource Heterogeneity on Evolutionary Diversification. Am Nat 2000; 155:769-789. [PMID: 10805643 DOI: 10.1086/303357] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A model is presented to explore how the form of selection arising from competition for resources is affected by spatial resource heterogeneity. The model consists of a single species occupying two patches connected by migration, where the two patches can differ in the type of resources that they contain. The main goal is to determine the conditions under which competition for resources results in disruptive selection (i.e., selection favoring a polymorphism) since it is this form of selection that will give rise to the evolutionary diversification of resource exploitation strategies. In particular, comparing the conditions giving rise to disruptive selection when the two patches are identical to the conditions when they contain different resources reveals the effect of spatial resource heterogeneity. Results show that when the patches are identical, the conditions giving rise to disruptive selection are identical to those that give rise to character displacement in previous models. When the patches are different, the conditions giving rise to disruptive selection can be either more or less stringent depending upon demographic parameters such as the intrinsic rate of increase and the migration rate. Surprisingly, spatial resource heterogeneity can actually make forms of evolutionary diversification such as character displacement less likely. It is also found that results are dependent on how the resource exploitation strategies and the spatial resource heterogeneity affect the population dynamics. One robust conclusion however, is that spatial resource heterogeneity always has a disruptive effect when the migration rate between patches is low.
Collapse
|
139
|
Abstract
To a first approximation, the distribution of biodiversity across the Earth can be described in terms of a relatively small number of broad-scale spatial patterns. Although these patterns are increasingly well documented, understanding why they exist constitutes one of the most significant intellectual challenges to ecologists and biogeographers. Theory is, however, developing rapidly, improving in its internal consistency, and more readily subjected to empirical challenge.
Collapse
Affiliation(s)
- K J Gaston
- Department of Animal and Plant Sciences, University of Sheffield, UK.
| |
Collapse
|
140
|
Abstract
The greater latitudinal extents of occurrence of species towards higher latitudes has been attributed to the broadening of physiological tolerances with latitude as a result of increases in climatic variation. While there is some support for such patterns in climate, the physiological tolerances of species across large latitudinal gradients have seldom been assessed. Here we report findings for insects based on published upper and lower lethal temperature data. The upper thermal limits show little geographical variation. In contrast, the lower bounds of supercooling points and lower lethal temperatures do indeed decline with latitude. However, this is not the case for the upper bounds, leading to an increase in the variation in lower lethal limits with latitude. These results provide some support for the physiological tolerance assumption associated with Rapoport's rule, but highlight the need for coupled data on species tolerances and range size.
Collapse
Affiliation(s)
- A Addo-Bediako
- Department of Zoology and Entomology, University of Pretoria, South Africa
| | | | | |
Collapse
|
141
|
Rex MA, Stuart CT, Coyne G. Latitudinal gradients of species richness in the deep-sea benthos of the North Atlantic. Proc Natl Acad Sci U S A 2000; 97:4082-5. [PMID: 10759545 PMCID: PMC18155 DOI: 10.1073/pnas.050589497] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Latitudinal species diversity gradients (LSDGs) in the Northern Hemisphere are the most well established biogeographic patterns on Earth. Despite long-standing interest in LSDGs as a central problem in ecology, their explanation remains uncertain. In terrestrial as well as coastal and pelagic marine ecosystems, these poleward declines in diversity typically have been represented and interpreted in terms of species richness, the number of coexisting species. Newly discovered LSDGs in the bathyal (500-4,000 m) benthos of the North Atlantic may help to resolve the underlying causes of these large-scale trends because the deep sea is such a physically distinct environment. However, a major problem in comparing surface and deep-sea LSDGs is that the latter have been measured differently, by using species diversity indices that are affected by both species richness and the evenness of relative abundance. Here, we demonstrate that deep-sea isopods, gastropods, and bivalves in the North Atlantic do exhibit poleward decreases in species richness, just as those found in other environments. A comprehensive systematic revision of the largest deep-sea gastropod family (Turridae) has provided a unique database on geographic distributions that is directly comparable to those used to document LSDGs in surface biotas. This taxon also shows a poleward decline in the number of species. Seasonal organic enrichment from sinking phytodetritus is the most plausible ecological explanation for deep-sea LSDGs and is the environmental factor most consistently associated with depressed diversity in a variety of bathyal habitats.
Collapse
Affiliation(s)
- M A Rex
- Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
| | | | | |
Collapse
|
142
|
Abstract
Eukaryotes often form symbioses with microorganisms. Among these, associations between plants and nitrogen-fixing bacteria are responsible for the nitrogen input into various ecological niches. Plants of many different families have evolved the capacity to develop root or stem nodules with diverse genera of soil bacteria. Of these, symbioses between legumes and rhizobia (Azorhizobium, Bradyrhizobium, Mesorhizobium, and Rhizobium) are the most important from an agricultural perspective. Nitrogen-fixing nodules arise when symbiotic rhizobia penetrate their hosts in a strictly controlled and coordinated manner. Molecular codes are exchanged between the symbionts in the rhizosphere to select compatible rhizobia from pathogens. Entry into the plant is restricted to bacteria that have the "keys" to a succession of legume "doors". Some symbionts intimately associate with many different partners (and are thus promiscuous), while others are more selective and have a narrow host range. For historical reasons, narrow host range has been more intensively investigated than promiscuity. In our view, this has given a false impression of specificity in legume-Rhizobium associations. Rather, we suggest that restricted host ranges are limited to specific niches and represent specialization of widespread and more ancestral promiscuous symbioses. Here we analyze the molecular mechanisms governing symbiotic promiscuity in rhizobia and show that it is controlled by a number of molecular keys.
Collapse
Affiliation(s)
- X Perret
- Laboratoire de Biologie Moléculaire des Plantes Supérieures, Université de Genève, 1292 Chambésy/Geneva, Switzerland
| | | | | |
Collapse
|
143
|
Roy K, Jablonski D, Valentine JW. Dissecting latitudinal diversity gradients: functional groups and clades of marine bivalves. Proc Biol Sci 2000; 267:293-9. [PMID: 10714884 PMCID: PMC1690525 DOI: 10.1098/rspb.2000.0999] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The latitudinal diversity gradient, with maximum taxonomic richness in the tropics, is widely accepted as being pervasive on land, but the existence of this pattern in the sea has been surprisingly controversial. This is partly due to Thorson's influential claim that the normal latitudinal diversity gradient occurs in marine epifauna (taxa living on the surface of the substratum) but not in infauna (burrowing or boring into the substratum), a contrast he attributed to the greater spatial and temporal environmental homogeneity of infaunal habitats. In an analysis of 930 species of north-eastern Pacific marine shelf bivalves, we found that bivalves as a whole, and both infauna and epifauna separately, show a strong latitudinal diversity gradient (measured as number of species per degree latitude) that is closely related to mean sea surface temperature (SST), even in analyses of residuals and first differences. This agrees with results for marine gastropods, but contradicts Thorson's environmental homogeneity hypothesis. The relationship between SST and diversity is consistent with a species-energy hypothesis, but the linkages from SST to diversity remain unclear. Most bivalve clades within broad functional groups conform to the general latitudinal trend, except for the deposit-feeding protobranchs. This group's non-directional pattern may be related to its mode of development, because a similar effect is seen in several other groups locked into this low-fecundity, non-feeding larval mode.
Collapse
Affiliation(s)
- K Roy
- Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA.
| | | | | |
Collapse
|
144
|
Jablonski D, Roy K, Valentine JW. Analysing the latitudinal diversity gradient in marine bivalves. ACTA ACUST UNITED AC 2000. [DOI: 10.1144/gsl.sp.2000.177.01.24] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractMarine bivalves of the eastern Pacific continental shelf show a strong diversity gradient from the Arctic Ocean to the tropics. This gradient is underlain by strong diversity trends in both infaunal and epifaunal bivalves, contrary to Thorson’s influential hypothesis (1952, Verhandlungen der Deutschen Zoologischen Gesellschaft, 1951, 267–327), and is significantly correlated with mean sea-surface temperature; either raw data or a residuals analysis yields p < 0.0001. Patterns differ according to trophic group and phylogeny; however, suspension feeders conform to the general bivalve diversity gradient, as do facultative deposit feeders such as tellinids, while deposit feeding protobranchs do not. Infaunal and epifaunal diversity gradients have different slopes so that their ratio changes with latitude; data on Jurassic and Cretaceous bivalves suggests that this ratio has varied in slope and intercept over geological time.
Collapse
Affiliation(s)
- David Jablonski
- Department of Geophysical Sciences, University of Chicago
5734 South Ellis Avenue, Chicago, IL 60637, USA
| | - Kaustuv Roy
- Department of Biology, University of California at San Diego
9500 Gilman Drive, La Jolla, CA 92093-0116, USA
| | - James W. Valentine
- Department of Integrative Biology, University of California
Berkeley, CA 94720, USA
| |
Collapse
|
145
|
SNELGROVE PAULVR, AUSTEN MELANIEC, BOUCHER GUY, HEIP CARLO, HUTCHINGS PATRICIAA, KING GARYM, KOIKE ISAO, LAMBSHEAD PJOHND, SMITH CRAIGR. Linking Biodiversity Above and Below the Marine Sediment–Water Interface. Bioscience 2000. [DOI: 10.1641/0006-3568(2000)050[1076:lbaabt]2.0.co;2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
146
|
Abstract
AbstractBivalves have been fundamental in developing the understanding of large-scale biodiversity patterns in the marine realm. A new study based on 29 regional bivalve faunas indicates that both latitudinal and longitudinal gradients are not so regular in form as was once imagined. The northern hemisphere latitudinal gradient has a marked step, or inflection, at 20–30°N, and in the southern hemisphere Australia forms a distinct diversity hotspot. A longitudinal gradient runs between a large tropical high diversity focus in the southern China-Indonesia-Australia region and a somewhat smaller one in the Panamic-Caribbean region.It is unlikely that the marked asymmetry in both latitudinal and longitudinal gradients can be explained entirely by either the geometric patterns of species ranges in relation to geographical boundaries (the mid-domain effect) or the operation of contemporary, or equilibrium, factors. The role of history must be considered too, and in some cases this could involve a timescale of at least 60 Ma. For example, Australia has moved progressively northwards throughout the Cenozoic era and this seems to have led to the development of a unique assemblage of both tropical and temperate taxa around the continent. When Australia eventually collided with southeast Asia, some 15 Ma ago, three previously distinct tropical marine faunas were brought into close juxtaposition.However, something else seems to have been involved in order to generate a marked pantropical Neogene diversification event in bivalves and other marine invertebrate taxa. It is striking how this event coincided with a prolonged interval of global cooling and the suggestion has been made that glacioeustatic cycles may have promoted the formation of a tropical species diversity pump. In concert with regular and profound sea-level changes, new taxa were created in marginal tropical regions and then concentrated in certain core regions. These same glacioeustatic cycles may also have served to accentuate the latitudinal limits of many tropical taxa.As the knowledge of large-scale taxonomic diversity gradients in the marine realm has increased, so too has the realization that they are at least the partial products of major historical events.
Collapse
Affiliation(s)
- J. A. Crame
- British Antarctic Survey
High Cross, Madingley Road, Cambridge CB3 0ET, UK
| |
Collapse
|
147
|
Chow SL, Clarke A. Stress and the Geographic Distribution of Marine and Terrestrial Animals. CELL AND MOLECULAR RESPONSE TO STRESS 2000. [DOI: 10.1016/s1568-1254(00)80006-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
148
|
|
149
|
Buzas MA, Culver SJ. Understanding regional species diversity through the log series distribution of occurrences. BIODIVERSITY RESEARCH. DIVERS DISTRIB 1999. [DOI: 10.1046/j.1472-4642.1999.00051.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
150
|
Pueppke SG, Broughton WJ. Rhizobium sp. strain NGR234 and R. fredii USDA257 share exceptionally broad, nested host ranges. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1999; 12:293-318. [PMID: 10188270 DOI: 10.1094/mpmi.1999.12.4.293] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Genetically, Rhizobium sp. strain NGR234 and R. fredii USDA257 are closely related. Small differences in their nodulation genes result in NGR234 secreting larger amounts of more diverse lipo-oligosaccharidic Nod factors than USDA257. What effects these differences have on nodulation were analyzed by inoculating 452 species of legumes, representing all three subfamilies of the Leguminosae, as well as the nonlegume Parasponia andersonii, with both strains. The two bacteria nodulated P. andersonii, induced ineffective outgrowths on Delonix regia, and nodulated Chamaecrista fasciculata, a member of the only nodulating genus of the Caesalpinieae tested. Both strains nodulated a range of mimosoid legumes, especially the Australian species of Acacia, and the tribe Ingeae. Highest compatibilities were found with the papilionoid tribes Phaseoleae and Desmodieae. On Vigna spp. (Phaseoleae), both bacteria formed more effective symbioses than rhizobia of the "cowpea" (V. unguiculata) miscellany. USDA257 nodulated an exact subset (79 genera) of the NGR234 hosts (112 genera). If only one of the bacteria formed effective, nitrogen-fixing nodules it was usually NGR234. The only exceptions were with Apios americana, Glycine max, and G. soja. Few correlations can be drawn between Nod-factor substituents and the ability to nodulate specific legumes. Relationships between the ability to nodulate and the origin of the host were not apparent. As both P. andersonii and NGR234 originate from Indonesia/Malaysia/Papua New Guinea, and NGR234's preferred hosts (Desmodiinae/Phaseoleae) are largely Asian, we suggest that broad host range originated in Southeast Asia and spread outward.
Collapse
Affiliation(s)
- S G Pueppke
- Department of Plant Pathology, University of Missouri, Columbia 65211, USA
| | | |
Collapse
|