Phenotypic plasticity determines differences between the skulls of tigers from mainland Asia

Tiger subspecific taxonomy is controversial because of morphological and genetic variation found between now fragmented populations, yet the extent to which phenotypic plasticity or genetic variation affects phenotypes of putative tiger subspecies has not been explicitly addressed. In order to assess the role of phenotypic plasticity in determining skull variation, we compared skull morphology among continental tigers from zoos and the wild. In turn, we examine continental tiger skulls from across their wild range, to evaluate how the different environmental conditions experienced by individuals in the wild can influence morphological variation. Fifty-seven measurements from 172 specimens were used to analyse size and shape differences among wild and captive continental tiger skulls. Captive specimens have broader skulls, and shorter rostral depths and mandible heights than wild specimens. In addition, sagittal crest size is larger in wild Amur tigers compared with those from captivity, and it is larger in wild Amur tigers compared with other wild continental tigers. The degree of phenotypic plasticity shown by the sagittal crest, skull width and rostral height suggests that the distinctive shape of Amur tiger skulls compared with that of other continental tigers is mostly a phenotypically plastic response to differences in their environments

Comparison of cranial performance between mainland and two island subspecies of the Arctic fox Vulpes lagopus (Carnivora: Canidae) during simulated biting

Island subspecies of the Arctic fox Vulpes lagopus differ morphologically from the mainland subspecies. In particular, differences in cranial form may reflect varied biomechanical adaptations associated with hunting and feeding behaviours. We tested the hypothesis that the observed cranial differences between two island foxes (living on two North Pacific islands) and those living on the mainland have no impact on biomechanical performance during simulated biting. 3D cranial models of three Arctic fox subspecies were compared based on biomechanical parameters (e.g. local strain and large-scale deformation). Finite elements (FE) analyses were used to simulate equivalent biting loads, and geometric morphometrics was used to compare the modes of deformation among the models. The results showed differences in local strains and modes of global deformation among the three subspecies; the mainland subspecies was particularly distinct from the island subspecies. The representative cranium of the mainland subspecies experienced higher strain than that of both island subspecies during all bites. However, the findings highlight issues that arise when relating biomechanical performance, measured via FE analyses, to the foods consumed rather than to the mechanical properties of the individual’s diet. Additional physical properties data for each prey type are necessary to determine the extent to which the present findings reflect biomechanical adaptations to diet and prey acquisition

Comparison of cranial performance between mainland and two island subspecies of the Arctic fox Vulpes lagopus (Carnivora: Canidae) during simulated biting

Island subspecies of the Arctic fox Vulpes lagopus differ morphologically from the mainland subspecies. In particular, differences in cranial form may reflect varied biomechanical adaptations associated with hunting and feeding behaviours. We tested the hypothesis that the observed cranial differences between two island foxes (living on two North Pacific islands) and those living on the mainland have no impact on biomechanical performance during simulated biting. 3D cranial models of three Arctic fox subspecies were compared based on biomechanical parameters (e.g. local strain and large-scale deformation). Finite elements (FE) analyses were used to simulate equivalent biting loads, and geometric morphometrics was used to compare the modes of deformation among the models. The results showed differences in local strains and modes of global deformation among the three subspecies; the mainland subspecies was particularly distinct from the island subspecies. The representative cranium of the mainland subspecies experienced higher strain than that of both island subspecies during all bites. However, the findings highlight issues that arise when relating biomechanical performance, measured via FE analyses, to the foods consumed rather than to the mechanical properties of the individual’s diet. Additional physical properties data for each prey type are necessary to determine the extent to which the present findings reflect biomechanical adaptations to diet and prey acquisition

Cranial features of mainland and Commander Islands (Russia) Arctic foxes (Vulpes lagopus) reflect their diverging foraging strategies

Populations of Arctic fox (Vulpes lagopus) in the Commander Islands, in the Russian Bering Sea, have been isolated since the Pleistocene and differ substantially in their cranial features from their mainland counterpart. Small rodents, the main prey of mainland Arctic foxes, are not found in the Commander Islands, where the main food source for Arctic foxes are large sea birds and marine mammals. Here we assessed whether differences in foraging strategy, particularly the size of available prey, could explain the observed differences in cranial features between mainland and island Arctic foxes. Because a large gape is necessary when foraging on large prey, we compared gape angles between islands and mainland in a sample of dry crania. We found an enlarged gape angle in both island populations. We also compared the rostrum to cranium length ratio and found it to be similar for the mainland and Bering Island Arctic foxes; however, a rostrum contraction was found in the Mednyi Island Arctic foxes. We show that cranial differences between mainland and Commander Islands fox populations could be explained by their different foraging ecology. Furthermore, the relative rostrum contraction in the Mednyi Island foxes provides further evidence for cranial resistance to deformation during biting. These results show the importance that distinct foraging strategies can have in Arctic fox divergent evolution, and, consequently, on future conservation plans for the two Commander Islands subspecies

figure 1 in Zebrus pallaoroi sp. nov.: a new species of goby (Actinopterygii: Gobiidae) from the Mediterranean Sea with a DNA-based phylogenetic analysis of the Gobius-lineage

figure 1 Preserved specimens. (A) Zebrus pallaoroi sp. nov., npm P6V144302, holotype, male, 31.81 + 8.51 mm, Kostanjica, Boka Kotorska, Adriatic Sea, Montenegro. Photo by M. Kovačić. (B) Zebrus zebrus, nmp P6V 140912, neotype, female, 23.25 + 6.22 mm, Îll Gross, Banyuls sur Mer, France (C) Millerigobius macrocephalus, nmp P6V 142686, juvenile of unidentified sex, 14.28 + 3.97 mm, Îll Gross, Banyuls sur Mer, France.Published as part of Cooper, David, Yamaguchi, Nobuyuki, Macdonald, David, Nanova, Olga, Yudin, Viktor, Dugmore, Andrew & Kitchener, Andrew, 2021, Zebrus pallaoroi sp. nov.: a new species of goby (Actinopterygii: Gobiidae) from the Mediterranean Sea with a DNA-based phylogenetic analysis of the Gobius-lineage, pp. 285-317 in Contributions to Zoology 90 (1) on page 295, DOI: 10.1163/18759866-bja10018, http://zenodo.org/record/834338

FIGURE 5 in Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry

FIGURE 5 Otoliths (mesial view) of Gobius bucchichi (a–c: Selce, 3l, 1l, 4l), G. cruentatus (d–f: Selce, 2l, 3l, 8l), G. niger (g–i: Pilsey Island, 2l, 6l, 5l) and G. roulei (j–l: Selce, 2l, 1l, 3l). Numbers following the localities refer to the fish specimen from which the otolith was extracted; l, left otolith. SL denotes the standard length (in mm) of the corresponding fish specimen. Scale bars: 0.5 mm. All figured otoliths are kept in the Bavarian State Collection (collection number SNSB-BSPG 2020 LIV).Published as part of Cooper, David, Yamaguchi, Nobuyuki, Macdonald, David, Nanova, Olga, Yudin, Viktor, Dugmore, Andrew & Kitchener, Andrew, 2020, Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry, pp. 282-323 in Contributions to Zoology 89 (1) on page 308, DOI: 10.1163/18759866-bja10002, http://zenodo.org/record/834325

FIGURE 4 in Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry

FIGURE 4 Otoliths (mesial view) of Gobius cobitis (a–c: Montenegro, 7l, 4l, 1l), G. geniporus (d: Montenegro, 3l; e, f: Selce, 2l, 'medium'), G. incognitus (g–i: Pelješac Peninsula, J1914l, J1910r mirrored, J1906l), G. paganellus (j–l: Galicia, 1l, 6l, 8l) and G. vittatus (m, Selce, 2l; n, o, Krk, Krk, 1l; 2l; p: Selce 2l). Numbers following the localities refer to the fish specimen from which the otolith was extracted; l, left otolith; r, right otolith, mirrored for better comparison. SL denotes the standard length (in mm) of the corresponding fish specimen. Scale bars: 0.5 mm. All figured otoliths are kept in the Bavarian State Collection (collection number SNSB-BSPG 2020 LIV).Published as part of Cooper, David, Yamaguchi, Nobuyuki, Macdonald, David, Nanova, Olga, Yudin, Viktor, Dugmore, Andrew & Kitchener, Andrew, 2020, Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry, pp. 282-323 in Contributions to Zoology 89 (1) on page 307, DOI: 10.1163/18759866-bja10002, http://zenodo.org/record/834325

FIGURE 6 in Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry

FIGURE 6 Otoliths (mesial view) of Pomatoschistus knerii (a–d: Krk, 1r, 2r, each mirrored, 9l, 4r mirrored), P. marmoratus (e–h: Selce, 1r, 2r, 3r, each mirrored, 4l), P. microps (i–l: Stralsund, 8l, 5l, 6l, 14l), P. minutus (m: Stralsund, 1l), P. montenegrensis (n–p: Skadar lake, 8l, 9l, 6l), P. pictus (m: Norway, 2r mirrored), and P. quagga (r–t: Krk, 2l, 8r mirrored, 4l). Numbers following the localities refer to the fish specimen from which the otolith was extracted; l, left otolith; r, right otolith, mirrored for better comparison. SL denotes the standard length (in mm) of the corresponding fish specimen. Scale bars: 0.5 mm. All figured otoliths are kept in the Bavarian State Collection (collection number SNSB-BSPG 2020 LIV). Downloaded from Brill.com10/07/2022 07:35:45PM via free accessPublished as part of Cooper, David, Yamaguchi, Nobuyuki, Macdonald, David, Nanova, Olga, Yudin, Viktor, Dugmore, Andrew & Kitchener, Andrew, 2020, Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry, pp. 282-323 in Contributions to Zoology 89 (1) on page 309, DOI: 10.1163/18759866-bja10002, http://zenodo.org/record/834325

figure 7 in Zebrus pallaoroi sp. nov.: a new species of goby (Actinopterygii: Gobiidae) from the Mediterranean Sea with a DNA-based phylogenetic analysis of the Gobius-lineage

figure 7 Haplotype networks constructed by a statistical parsimony method based on cytochrome b gene sequences. The number of mutational steps between the two closest haplotypes is indicated by hatch marks. Missing intermediate haplotypes are shown as small black circles.Published as part of Cooper, David, Yamaguchi, Nobuyuki, Macdonald, David, Nanova, Olga, Yudin, Viktor, Dugmore, Andrew & Kitchener, Andrew, 2021, Zebrus pallaoroi sp. nov.: a new species of goby (Actinopterygii: Gobiidae) from the Mediterranean Sea with a DNA-based phylogenetic analysis of the Gobius-lineage, pp. 285-317 in Contributions to Zoology 90 (1) on page 308, DOI: 10.1163/18759866-bja10018, http://zenodo.org/record/834338