Chapter 11: Global Climate and the Evolution of Large Mammalian Carnivores during the Later Cenozoic in North America

Parallelism and lineage replacement of the late Miocene scimitar-toothed cats from the old and New World

In contrast to large-scale convergence/parallelism, the small-scale convergence/parallelism of sabertooth adaptation within closely related genera and species has been seldom investigated. Here, we describe and analyze the rich material of Nimravides catocopis, and provide evidence using a new phylogenetic analysis that Nimravides was endemic to North America. The late Miocene (10.5-6.5 Ma) Nimravides represents a lineage that shows clearly parallelism with the contemporary Old World lineage of Machairodus-Amphimachairodus.The Old World lineage experienced a higher evolutionary rate of cranial trait than the New World one did. The low density of Amphimachairodus at its first appearance in North America suggests that the derived traits did not provide a direct competitive advantage over Nimravides, but allowed Amphimachairodus to survive the significant faunal change in the early-late Hemphillian (∼6.5 Ma) in North America, a process that probably can be applied to most replacement of closely related lineages.

Continental faunal exchange and the asymmetrical radiation of carnivores

Lineages arriving on islands may undergo explosive evolutionary radiations owing to the wealth of ecological opportunities. Although studies on insular taxa have improved our understanding of macroevolutionary phenomena, we know little about the macroevolutionary dynamics of continental exchanges. Here we study the evolution of eight Carnivora families that have migrated across the Northern Hemisphere to investigate if continental invasions also result in explosive diversification dynamics. We used a Bayesian approach to estimate speciation and extinction rates from a substantial dataset of fossil occurrences while accounting for the incompleteness of the fossil record. Our analyses revealed a strongly asymmetrical pattern in which North American lineages invading Eurasia underwent explosive radiations, whereas lineages invading North America maintained uniform diversification dynamics. These invasions into Eurasia were characterized by high rates of speciation and extinction. The radiation of the arriving lineages in Eurasia coincide with the decline of established lineages or phases of climate change, suggesting differences in the ecological settings between the continents may be responsible for the disparity in diversification dynamics. These results reveal long-term outcomes of biological invasions and show that the importance of explosive radiations in shaping diversity extends beyond insular systems and have significant impact at continental scales.

North or south? Phylogenetic and biogeographic origins of a globally distributed avian clade

Establishing phylogenetic relationships within a clade can help to infer ancestral origins and indicate how widespread species reached their current biogeographic distributions. The small plovers, genus Charadrius, are cosmopolitan shorebirds, distributed across all continents except Antarctica. Here we present a global, species-level molecular phylogeny of this group based on four nuclear (ADH5, FIB7, MYO2 and RAG1) and two mitochondrial (COI and ND3) genes, and use the phylogeny to examine the biogeographic origin of the genus. A Bayesian multispecies coalescent approach identified two major clades (CRD I and CRD II) within the genus. Clade CRD I contains three species (Thinornis novaeseelandiae, Thinornis rubricollis and Eudromias morinellus), and CRD II one species (Anarhynchus frontalis), that were previously placed outside the Charadrius genus. In contrast to earlier work, ancestral area analyses using parsimony and Bayesian methods supported an origin of the Charadrius plovers in the Northern hemisphere. We propose that major radiations in this group were associated with shifts in the range of these ancestral plover species, leading to colonisation of the Southern hemisphere.

Phylogeny and biogeography of bees of the tribe Osmiini (Hymenoptera: Megachilidae)

The Osmiini (Megachilidae) constitute a taxonomically and biologically diverse tribe of bees. To resolve their generic and suprageneric relationships, we inferred a phylogeny based on three nuclear genes (Elongation factor 1-alpha, LW-rhodopsin and CAD) applying both parsimony and Bayesian methods. Our phylogeny, which includes 95 osmiine species representing 18 of the 19 currently recognized genera, is well resolved with high support for most basal nodes. The core osmiine genera were found to form a well-supported monophyletic group, but four small genera, Noteriades, Afroheriades,Pseudoheriades and possibly Ochreriades, formerly included in the Osmiini, do not appear to belong within this tribe. Our phylogeny results in the following taxonomic changes: Stenosmia and Hoplosmia are reduced to subgeneric rank in Hoplitis and Osmia, respectively, Micreriades is recognized as a subgenus in Hoplitis and the subgenus Nasutosmia is transferred from Hoplitis to Osmia. We inferred a biogeographic scenario for the Osmiini applying maximum likelihood inference and models of character evolution. We provide evidence that the Osmiini originated in the Palearctic, and that extensive exchanges occurred between the Palearctic and the Nearctic. The latter finding may relate to the fact that many osmiine species nest in wood or in stems, facilitating dispersal by overseas transport of the nests.