Insular dwarfism in canids on Java (Indonesia) and its implication for the environment of Homo erectus during the Early and earliest Middle Pleistocene

Geer, Alexandra van der; Lyras, George; Volmer, Rebekka

doi:10.1016/j.palaeo.2018.07.009

Cited by 11 publications

(11 citation statements)

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“…Cranial shape changes proportional to changes in size are found in dwarfed elephants, for instance Palombo, 2001). These changes are follow mainland allometric patterns suggesting that the decreased pneumatization of the skull of the dwarf elephant (Elephas falconeri) does not represent an adaptation but just a change in shape related to decreased cranial size (van der Geer et al, 2018). Relatively larger molars (hypsodonty) and missing premolars are also often found in dwarfed forms and likely represent changes in skeletal traits due to changes in size .…”

Section: Body Shape Evolutionmentioning

confidence: 84%

“…Body size is intimately connected with the dietary and reproductive strategies of an organism (Kleiber, 1932;Charnov, 1991;West et al, 1997;Jeschke and Kokko, 2009), and in island areas (with different population and community dynamics compared to the mainland) organisms often evolve a divergent body size (Foster, 1963(Foster, , 1965Van Valen, 1973;Heaney, 1978;Lawlor, 1982;Anderson and Handley, 2002;Meiri, 2007Meiri, , 2008Pafilis et al, 2009;Jaffe et al, 2011;van der Geer et al, 2013avan der Geer et al, , 2013bvan der Geer et al, , 2018Runemark et al, 2015;Benítez-López et al, 2020). Changes in body size are so prevalent on island areas that an ecological rule was developed to describe it (i.e., the island rule; Van Valen, 1973).…”

Section: Body Size Evolutionmentioning

confidence: 99%

“…Changes to skeletal traits may also arise as an adaptive response to novel island selective pressures. Dwarfed hippos, for instance, have anatomical reorganization of the skull that do not follow mainland allometric scaling trends and likely represent selection for cranial shape changes (van der Geer et al, 2018). Changes in limb length, orientation, and proportions are also extremely common in dwarfed mammals (such as Candiacervus and Hoplitomeryx (deer), Hippopatomus (hippo), Stegadon (stegodont), and Myotragus (goat; van der Geer, 2005van der Geer, , 2014.…”

Section: Body Shape Evolutionmentioning

confidence: 99%

“…The island rule is likely not a direct response to decreased nutrition (such as daily caloric intake), but a phenomenon that is highly context specific and relates to the evolved body size of the mainland organism and subsequent island ecological interactions. In many organisms there is little evidence for body size relating directly to island area (Meiri et al, , 2005van der Geer et al, 2018). For instance, carnivore body size alterations are not directly related to island area but the size of available prey species (van der Geer et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…In many organisms there is little evidence for body size relating directly to island area (Meiri et al, , 2005van der Geer et al, 2018). For instance, carnivore body size alterations are not directly related to island area but the size of available prey species (van der Geer et al, 2018). Carnivores on islands may adjust body size in response to available prey species as seen, for example, in the reduced limbs and skeletal size of the canid Cynotherium sardous in response to smaller sized prey .…”

Section: Introductionmentioning

confidence: 99%

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Body size and shape in insular environments and applications of the island rule in biological anthropology

Young¹

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The discovery of small-bodied hominin fossils in 2004 on the island of Flores, Indonesia, unearthed a large debate within biological anthropology. This debate has exemplified that there are questions and research areas that biological anthropologists do not understand about island evolution. To improve understanding on the causes and products of evolution within island areas for biological anthropologists, this dissertation addresses three overarching research areas relevant to the biological anthropology community. The first is an analysis of how primate body sizes vary on islands, with interpretations that are anchored in the evolutionary history of body sizes of primates. Primates that initially evolved body sizes to survive within a frugivorous niche, with elongated life spans to improve survival in unpredictable environments, have body sizes distributed among islands in relation to the presence of absence of these pressures. Smaller islands contain more large, bodied primates overall, whereas larger islands contain more small-bodied ones. Second, an analysis of island fox body size and shape indicates that island foxes have reduced body sizes and divergent skeletal traits compared to mainland, closely related counterparts. Distinct body proportions are likely due to selection because allometric scaling of limb lengths to body mass are divergent for the island fox. Further, the island fox is not a scaled down version of the mainland fox, with limbs decreasing in size at a faster rate compared to the mainland. Last, an investigation on the diversity of two human populations in the Baja California peninsula demonstrates that Amerindians who migrated to and survived in these regions were impacted by ecogeographic pressures in different degrees, likely related to access to resources. Heat-adapted skeletal traits are apparent in both human populations who inhabited this hot desert, but body size is distinct for the two groups. Body size is smaller for individuals with less access to marine resources and increased susceptibility to periods of drought and starvation. Body size is larger for humans with convenient access to oceanic and terrestrial resources. These studies demonstrate that primates, omnivores, and humans are not immune to the effects of insularity as has been suggested. Rather, interpreting body size and shape alterations requires contextualizing the organism with their evolutionary histories and subsequent interactions within the island areas. Body size alterations are the result of shifting selective pressures from competing with other community members to competing with other individuals within a population over finite resources. As such, body shape can also be divergent compared to closely related mainland counterparts due to adaptation to local ecogeographic pressures. Skeletal traits of organisms need to be interpreted in relation to their migratory journeys and adaptation to local ecogeographic pressures within the island. For humans, contextualizing these variables with cultural and behavioral characteristics is imperative to understand a body size response within a sociocultural omnivorous niche.

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Section: Body Shape Evolutionmentioning

confidence: 84%