Biogeographical variation on craniomandibular morphology in pallas’s squirrel \(\textit{Callosciurus erythraeus}\) (Pallas, 1779) (Rodentia: Sciuridae) in Vietnam

Different forest vegetations provide herbivorous small mammals with different resources, forcing adaptation since food habits depend on available resources. We expect differences in vegetation to be reflected in the size and shape of the skull and mandible as a result of potentially different feeding resources. Therefore, we analyzed the craniomandibular characteristics of Pallas’s squirrel (Callosciurus erythraeus) in Vietnam. This species commonly occurs in different vegetations in Vietnam, making it a good model for examining morphological adaptation to vegetation type. We analyzed morphologically the skulls and mandibles of 156 specimens collected from 31 localities in Vietnam from 1960 to the present. Principal component analysis showed that females occurring in the tropical lowland evergreen rain forest were clearly separated from those in other vegetations.

Assessment of the biogeographical variation of seed size and seed oil traits in wild Silphium integrifolium Michx. genotypes

Silphium spp. have garnered interest in Europe as a bioenergy crop and in North America as a perennial oilseed crop. However, very little has been done at this early stage of domestication to characterize wild collections for many key characteristics, including important oilseed traits. The objective of this work was to develop a basic understanding of how biogeography and associated population genetic forces have shaped seed phenotypes in plant collections across the native range of Silphium integrifolium Michx. (Asteraceae: Heliantheae), the primary domestication candidate for oilseed use. A collection of 53 accessions was grown in a common environment in Salina, KS, which is a location well within the native range of the species in central North America. Plants from each collection site were randomly mated by hand to produce seed representative of each accession, and the seeds subjected to seed dimensional trait, oil content and oil composition analyses. Kernel width varied along a latitudinal cline of collection site, while kernel length varied across a longitudinal cline. Palmitic and linoleic acids were inversely correlated with each other and varied along a longitudinal cline of the collection site. The results indicate that accessions collected from more southwesterly sites tended to have larger seed and those from more westerly sites had higher linoleic acid content and lower palmitic and myristic acids, which are all desirable phenotypes for an oilseed Silphium.

Evolutionary Geography and the Afrotropical Model of Hominin Evolution

During the second half of the twentieth century, the evidence that Africa was central to hominin evolution became overwhelming. The earliest occurrences of most of the fossil hominin taxa and lithic technologies are to be found in Africa, and there is also strong evidence that humans are closely related to African apes, and that the genetic origins of modern humans lie in Africa. The aim of this article is to consider the possible evolutionary and ecological basis for this — why should Africa be so central? After considering biases in the record that might promote an African record, this article uses evolutionary geography – the spatial and distributional properties of the evolutionary process — to consider the factors that lead to higher rates of speciation, novelty and dispersals, as well as the way in which the African ecological context is structured and changes through time. Critical factors identified are the variable role of the Sahara, the different extent of the Afrotropical realm as climate changes, the impact of basin structure, and the effect of variable topography and surface water distribution. The key factor is biogeographic regionalisation and the shared evolutionary histories that reflect this. It is proposed that hominin evolution is globally part of the Afrotropical realm and its history, and that biogeographical variation within Africa is a key to understand the diverse nature of African hominins and their potential to disperse beyond the continent. More broadly, this article shows the importance of placing hominin evolution into a comparative and theoretical framework, particularly evolutionary geography, and proposes a more general basis for the Afrotropical Model of Hominin Evolution.