Biological Journal of the Linnean Society

Kahrl, Ariel F; Hall, Hannah R; Carson, Isabela R; Johnson, Michele A

doi: 10.1093/biolinnean/blaf016pmid: N/A

The major function of the testes is the production of sperm cells. Across species there are dramatic differences in sperm morphology, and this variation may result from variation in the internal structure of the testis. Yet, the extent to which testis anatomy is associated with sperm size remains unclear. In this study, we used 20 species of Anolis lizards to examine interspecific relationships between testis architecture and sperm component lengths, as well as testis architecture and a proxy for copulation rate (hemipenis muscle damage), using both phylogenetic and regular linear models. Results of our evolutionary analysis indicate that testis and sperm components have high phylogenetic signal. Further, testis architecture and sperm component length, and the variance in these traits, are not associated with one another using phylogenetic linear models, although non-phylogenetic analyses suggest that larger testes produce sperm with longer flagella. Our interpretation of these conflicting models is that the strong phylogenetic signal of these traits may mask significant functional and developmental relationships in phylogenetic models that regular linear models reveal. This suggests that these traits are not experiencing selection that would cause these traits to covary in a different pattern than their phylogenetic relationships; instead, in this group they are likely evolving together neutrally.

Njuguna, Lynn Njeri; Ulrich, Werner; Mwakumanya, Maarifa Ali; Chiyo, Patrick; Habel, Jan Christian

doi: 10.1093/biolinnean/blaf015pmid: N/A

Elephants play a significant role in shaping tropical ecosystems. They influence the dispersal and regeneration of various plant species and thus shape plant and animal communities. In this study, we investigate seed predation rates by the African elephant on the torchwood forest tree (Balanites maughamii) in a part of the Arabuko Sokoke dry coastal forest in southern Kenya. We test for effects on the germination and seedling growth rates in ex situ experiments and consider the role of passing through the elephant gut and the effect of elephant dung on germination. Seed predation rates were highest close to parent trees. Seeds that passed through elephant guts had the highest germination and growth rates. Seeds enclosed by dung did not show higher rates of germination than seeds without dung. In general, our results underline the important role of elephants for seed dispersal and germination of B. maughamii in tropical forest ecosystems.