Convergence, Adaptation, and Constraint: Morphological Insights into Human and Mammalian Evolution
Morphological variation in mammals reflects a complex interplay of evolutionary convergence, environmental adaptation, and developmental constraint. In this talk, I explore three case studies that examine these ‘processes’ across different anatomical systems and taxa using 3D geometric morphometrics and a combination of existing and novel multivariate statistics.
First, I examine bony labyrinth (inner ear) morphology across Afrotheria and other mammalian clades. Despite deep phylogenetic divergence, species with similar ecological niches independently evolved similar labyrinth shapes—highlighting convergent evolution shaped by functional demands.
Second, I investigate cranial shape variation in long-tailed macaques (Macaca fascicularis) across the Sunda Shelf. Repeated sea level changes and associated fragmentation of Sundaland during the Pleistocene are often invoked as the main drivers of Southeast Asian mammalian differentiation. However, macaque skull shape is better explained by climate than by genetic structure or Quaternary biogeography – indicative of environmental adaptation rather than historical isolation.
Third, I present a quantitative comparison of pelvic sexual dimorphism in humans and chimpanzees. The two species show a near-identical pattern of shape differences between the sexes. This refutes the long-standing assumption that the human pattern evolved recently and de novo in response to the competing demands of bipedalism and obstetrics. However, the magnitude of dimorphism is much greater in humans, likely reflecting an adaptive response along a conserved developmental pathway to meet specific obstetric challenges.
Jonas Wolff
Universität Greifswald, Evolutionary Biomechanics, Zoological Institute and Museum & School of Natural Sciences, Macquarie University, Sydney, Australia
Germany
Tough threads, ballistic webs and bungee-jumps: evolutionary biomechanics of spider extended phenotypes
Spider silk is among the toughest known materials, enabling spiders to construct multi-functional architectures with a minimum of material investment. Spiders use these architectures (threads, webs, retreats and egg cases) as extended interfaces, which may impressively enhance predatory, defensive and locomotor capabilities. Spiders typically produce multiple types of silk secretions in differentiated glandular systems, that are connected to spinnerets – leg-like appendages equipped with various muscles that enable fine-scale movements. In this talk I give an overview about our latest research on how the structure and function of the spider spinning apparatus, silks and silk architectures changed over 400 million years of spider evolution. In particular, I will demonstrate how changes in spinning apparatus morphology enabled the evolution of novel behaviours and tougher silk threads. Further, I will show examples of how spiders may use silk architectures for power amplification, to subdue large prey and for rapid escape manoeuvres. These examples broaden the perspective of functional morphology, which does not only apply to body parts, but also to extended phenotypes, such as architectures formed by secretions.
