ABSTRACT
The Natural History Collections, Bergen Museum, The University of Bergen, Norway, houses a large collection of Baleen whale skeletons within which one mature Fin (Balaenoptera physalus) and one juvenile Humpback (Megaptera novaeangliae) whale skeleton exhibit notable osteological pathologies that are reported in this brief communication. The Humpback skeleton has a large lesion on the maxilla characterised by loss of bone and remodelling. The lesion would appear to be a healing injury caused by trauma to the area of the gums and adjacent soft tissue. This specimen also exhibits numerous localised areas of infection along the length of the vertebral column and bridging between two cervical vertebrae attributed to spondyloarthropathy. Such pathologies have rarely been reported in juvenile cetaceans. The Fin whale specimen exhibits eight rib fractures, which may be the result of a boat collision and numerous areas of excess bone growth at the superior edge of the vertebral spinous processes which are of unknown aetiology but may be a consequence of the forces acting upon the spine during aquatic locomotion or dysbaric osteonecrosis, caused by diving.
ABSTRACT
Sexual size dimorphism (SSD) is often assumed to be driven by three major selective processes: (1) sexual selection influencing male size and thus mating success, (2) fecundity selection acting on females and (3) inter-sexual resource division favouring different size in males and females to reduce competition for resources. Sexual selection should be particularly strong in species that exhibit lek polygyny, since male mating success is highly skewed in such species. We investigated whether these three selective processes are related to SSD evolution in grouse and allies (Phasianidae). Male-biased SSD increased with body size (Rensch's rule) and lekking species exhibited more male-biased SSD than nonlekking ones. Directional phylogenetic analyses indicated that lekking evolved before SSD, but conclusions were highly dependent on the body size traits and chosen model values. There was no relationship between SSD and male display agility, nor did resource division influence SSD. Although clutch mass increased with female body size it was not related to the degree of SSD. Taken together, the results are most consistent with the hypothesis that lekking behaviour led to the evolution of male-biased SSD in Phasianidae.
