1
|
Joseph GS, Seymour CL. Dispersal limitation and fire feedbacks maintain mesic savannas in Madagascar: Comment. Ecology 2023; 104:e4045. [PMID: 37261396 DOI: 10.1002/ecy.4045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 10/12/2022] [Accepted: 10/20/2022] [Indexed: 06/02/2023]
Affiliation(s)
- Grant S Joseph
- Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Colleen L Seymour
- Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, South Africa
| |
Collapse
|
2
|
Molecular exploration of fossil eggshell uncovers hidden lineage of giant extinct bird. Nat Commun 2023; 14:914. [PMID: 36854679 PMCID: PMC9974994 DOI: 10.1038/s41467-023-36405-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/31/2023] [Indexed: 03/02/2023] Open
Abstract
The systematics of Madagascar's extinct elephant birds remains controversial due to large gaps in the fossil record and poor biomolecular preservation of skeletal specimens. Here, a molecular analysis of 1000-year-old fossil eggshells provides the first description of elephant bird phylogeography and offers insight into the ecology and evolution of these flightless giants. Mitochondrial genomes from across Madagascar reveal genetic variation that is correlated with eggshell morphology, stable isotope composition, and geographic distribution. The elephant bird crown is dated to ca. 30 Mya, when Madagascar is estimated to have become less arid as it moved northward. High levels of between-clade genetic variation support reclassifying Mullerornis into a separate family. Low levels of within-clade genetic variation suggest there were only two elephant bird genera existing in southern Madagascar during the Holocene. However, we find an eggshell collection from Madagascar's far north that represents a unique lineage of Aepyornis. Furthermore, divergence within Aepyornis coincides with the aridification of Madagascar during the early Pleistocene ca. 1.5 Ma, and is consistent with the fragmentation of populations in the highlands driving diversification and the evolution of extreme gigantism over shorts timescales. We advocate for a revision of their taxonomy that integrates palaeogenomic and palaeoecological perspectives.
Collapse
|
3
|
Joseph GS, Seymour CL. Are Madagascar's obligate grazing-lawns ancient and evolved with endemic herbivores, or recently selected by introduced cattle? Biol Lett 2022; 18:20220212. [PMID: 36102011 PMCID: PMC9471269 DOI: 10.1098/rsbl.2022.0212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- Grant S Joseph
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa
| | - Colleen L Seymour
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa.,South African National Biodiversity Institute, Kirstenbosch, Claremont 7735, South Africa
| |
Collapse
|
4
|
Hansford JP, Turvey ST. Dietary isotopes of Madagascar's extinct megafauna reveal holocene browsing and grazing guilds. Biol Lett 2022; 18:20220094. [PMID: 35414222 PMCID: PMC9006009 DOI: 10.1098/rsbl.2022.0094] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Megafauna play a disproportionate role in developing and maintaining their biomes, by regulating plant dispersal, community structure and nutrient cycling. Understanding the ecological roles of extinct megafaunal communities, for example through dietary reconstruction using isotope analysis, is necessary to determine pre-human states and set evidence-based restoration goals. We use δ13C and δ15N isotopic analyses to reconstruct Holocene feeding guilds in Madagascar's extinct megaherbivores, which included elephant birds, hippopotami and giant tortoises that occurred across multiple habitats and elevations. We compare isotopic data from seven taxa and two elephant bird eggshell morphotypes against contemporary regional floral baselines to infer dietary subsistence strategies. Most taxa show high consumption of C3 and/or CAM plants, providing evidence of widespread browsing ecology. However, Aepyornis hildebrandti, an elephant bird restricted to the central highlands region, has isotope values with much higher δ13C values than other taxa. This species is interpreted as having obtained up to 48% of its diet from C4 grasses. These findings provide new evidence for distinct browsing and grazing guilds in Madagascar's Holocene megaherbivore fauna, with implications for past regional distribution of ecosystems dominated by endemic C4 grasses.
Collapse
Affiliation(s)
- James P Hansford
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK.,Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.,School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
| | - Samuel T Turvey
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| |
Collapse
|
5
|
Joseph GS, Rakotoarivelo AR, Seymour CL. Tipping points induced by palaeo-human impacts can explain presence of savannah in Malagasy and global systems where forest is expected. Proc Biol Sci 2022; 289:20212771. [PMID: 35350853 PMCID: PMC8965410 DOI: 10.1098/rspb.2021.2771] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Models aimed at understanding C4-savannah distribution for Australia, Africa and South America support transition to forest at high mean annual precipitation (MAP), and savannah grasslands of Madagascar have recently been reported to be similarly limited. Yet, when savannah/grassland presence data are plotted against MAP for the various ecosystems across the Malagasy Central Highlands, the relationship does not hold. Furthermore, it does not always hold in other sites on other continents. Instead, in high-rainfall savannahs, palaeo-human impacts appear to have selected a fire-adapted habitat, creating tipping points that allow savannah persistence despite high rainfall, suppressing forest return. We conducted the largest systematic literature review to date for global evidence of palaeo-human impacts in savannahs, and conclude that impacts are widespread and should be incorporated into models aimed at understanding savannah persistence at elevated precipitation, particularly as more palaeodata emerges. Building on existing studies, we refine the MAP savannah relationship at higher MAP. Palaeoanthropogenic impact can help explain inconsistencies in the savannah/forest boundary at higher MAP, and points to a key role for palaeoecology in understanding systems. Including these effects presents a crucial change to our understanding of factors determining global savannah distribution, supporting a human hand in much of their formation.
Collapse
Affiliation(s)
- Grant S. Joseph
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Rondebosch 7701, South Africa
| | - Andrinajoro R. Rakotoarivelo
- Afro-mountain Research Unit, The University of the Free State Qwaqwa, Private Bag X13, Phuthaditjhaba 9866, Republic of South Africa,Natiora Ahy, Lot IIU57 K Bis, Ampahibe, Antananarivo 101, Madagascar
| | - Colleen L. Seymour
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Rondebosch 7701, South Africa,South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont 7735, South Africa
| |
Collapse
|
6
|
Reinhardt AL, Kasper T, Lochner M, Bliedtner M, Krahn KJ, Haberzettl T, Shumilovskikh L, Rahobisoa JJ, Zech R, Favier C, Behling H, Bremond L, Daut G, Montade V. Rain Forest Fragmentation and Environmental Dynamics on Nosy Be Island (NW Madagascar) at 1300 cal BP Is Attributable to Intensified Human Impact. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.783770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Madagascar houses one of the Earth’s biologically richest, but also one of most endangered, terrestrial ecoregions. Although it is obvious that humans substantially altered the natural ecosystems during the past decades, the timing of arrival of early inhabitants on Madagascar as well as their environmental impact is still intensively debated. This research aims to study the beginning of early human impact on Malagasy natural ecosystems, specifically on Nosy Be island (NW Madagascar) by targeting the sedimentary archive of Lake Amparihibe, an ancient volcanic crater. Based on pollen, fungal spore, other non-pollen palynomorph, charcoal particle and diatom analyses combined with high-resolution sediment-physical and (in)organic geochemical data, paleoenvironmental dynamics during the past three millennia were reconstructed. Results indicate a major environmental change at ca. 1300 cal BP characterized by an abrupt development of grass (C4) dominated and fire disturbed landscape showing the alteration of natural rain forest. Further, increased soil erodibility is suggested by distinct increase in sediment accumulation rates, a strong pulse of nutrient input, higher water turbidity and contemporaneous increase in spores of mycorrhizal fungi. These parameters are interpreted to show a strong early anthropogenic transformation of the landscape from rain forest to open grassland. After ca. 1000 cal BP, fires remain frequent and vegetation is dominated by forest/grassland mosaic. While natural vegetation should be dominated by rain forest on Nosy Be, these last results indicate that human continuously impacted the landscapes surrounding the lake. At a local scale, our data support the “subsistence shift hypothesis” which proposed that population expansion with development of herding/farming altered the natural ecosystems. However, a precise regional synthesis is challenging, since high-resolution multi-proxy records from continuous sedimentary archives as well as records located further north and in the hinterland are still scarce in Madagascar. The lack of such regional synthesis also prevents precise comparison between different regions in Madagascar to detect potential (dis)similarities in climate dynamics, ecosystem responses and anthropogenic influences at the island’s scale during the (late) Holocene.
Collapse
|
7
|
Tofanelli S, Bertoncini S, Donati G. Early Human Colonization, Climate Change and Megafaunal Extinction in Madagascar: The Contribution of Genetics in a Framework of Reciprocal Causations. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.708345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
8
|
Hixon SW, Douglass KG, Godfrey LR, Eccles L, Crowley BE, Rakotozafy LMA, Clark G, Haberle S, Anderson A, Wright HT, Kennett DJ. Ecological Consequences of a Millennium of Introduced Dogs on Madagascar. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.689559] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Introduced predators currently threaten endemic animals on Madagascar through predation, facilitation of human-led hunts, competition, and disease transmission, but the antiquity and past consequences of these introductions are poorly known. We use directly radiocarbon dated bones of introduced dogs (Canis familiaris) to test whether dogs could have aided human-led hunts of the island’s extinct megafauna. We compare carbon and nitrogen isotope data from the bone collagen of dogs and endemic “fosa” (Cryptoprocta spp.) in central and southwestern Madagascar to test for competition between introduced and endemic predators. The distinct isotopic niches of dogs and fosa suggest that any past antagonistic relationship between these predators did not follow from predation or competition for shared prey. Radiocarbon dates confirm that dogs have been present on Madagascar for over a millennium and suggest that they at least briefly co-occurred with the island’s extinct megafauna, which included giant lemurs, elephant birds, and pygmy hippopotamuses. Today, dogs share a mutualism with pastoralists who also occasionally hunt endemic vertebrates, and similar behavior is reflected in deposits at several Malagasy paleontological sites that contain dog and livestock bones along with butchered bones of extinct megafauna and extant lemurs. Dogs on Madagascar have had a wide range of diets during the past millennium, but relatively high stable carbon isotope values suggest few individuals relied primarily on forest bushmeat. Our newly generated data suggest that dogs were part of a suite of animal introductions beginning over a millennium ago that coincided with widespread landscape transformation and megafaunal extinction.
Collapse
|
9
|
Lehmann CER, Solofondranohatra CL, Vorontsova MS. Beyond ancient versus anthropogenic for Madagascar's grassy ecosystems. A Reply to: Crowley et al. (2021). Proc Biol Sci 2021; 288:20210388. [PMID: 33978522 PMCID: PMC8115201 DOI: 10.1098/rspb.2021.0388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/19/2021] [Indexed: 12/29/2022] Open
Affiliation(s)
- Caroline E. R. Lehmann
- Tropical Diversity, Royal Botanic Garden Edinburgh, UK
- School of GeoSciences, University of Edinburgh, UK
| | - Cédrique L. Solofondranohatra
- Laboratoire de Botanique, Département de Biologie et Ecologie Végétales, Faculté des Sciences, Université d'Antananarivo, Madagascar
- Kew Madagascar Conservation Centre, Ambodivoanjo, Antananarivo, Madagascar
| | | |
Collapse
|