36 research outputs found

    Kiwi Forego Vision in the Guidance of Their Nocturnal Activities

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    BACKGROUND: In vision, there is a trade-off between sensitivity and resolution, and any eye which maximises information gain at low light levels needs to be large. This imposes exacting constraints upon vision in nocturnal flying birds. Eyes are essentially heavy, fluid-filled chambers, and in flying birds their increased size is countered by selection for both reduced body mass and the distribution of mass towards the body core. Freed from these mass constraints, it would be predicted that in flightless birds nocturnality should favour the evolution of large eyes and reliance upon visual cues for the guidance of activity. METHODOLOGY/PRINCIPAL FINDINGS: We show that in Kiwi (Apterygidae), flightlessness and nocturnality have, in fact, resulted in the opposite outcome. Kiwi show minimal reliance upon vision indicated by eye structure, visual field topography, and brain structures, and increased reliance upon tactile and olfactory information. CONCLUSIONS/SIGNIFICANCE: This lack of reliance upon vision and increased reliance upon tactile and olfactory information in Kiwi is markedly similar to the situation in nocturnal mammals that exploit the forest floor. That Kiwi and mammals evolved to exploit these habitats quite independently provides evidence for convergent evolution in their sensory capacities that are tuned to a common set of perceptual challenges found in forest floor habitats at night and which cannot be met by the vertebrate visual system. We propose that the Kiwi visual system has undergone adaptive regressive evolution driven by the trade-off between the relatively low rate of gain of visual information that is possible at low light levels, and the metabolic costs of extracting that information

    A new, large-bodied omnivorous bat (Noctilionoidea: Mystacinidae) reveals lost morphological and ecological diversity since the Miocene in New Zealand

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    A new genus and species of fossil bat is described from New Zealand's only pre-Pleistocene Cenozoic terrestrial fauna, the early Miocene St Bathans Fauna of Central Otago, South Island. Bayesian total evidence phylogenetic analysis places this new Southern Hemisphere taxon among the burrowing bats (mystacinids) of New Zealand and Australia, although its lower dentition also resembles Africa's endemic sucker-footed bats (myzopodids). As the first new bat genus to be added to New Zealand's fauna in more than 150 years, it provides new insight into the original diversity of chiropterans in Australasia. It also underscores the significant decline in morphological diversity that has taken place in the highly distinctive, semi-terrestrial bat family Mystacinidae since the Miocene. This bat was relatively large, with an estimated body mass of ~40 g, and its dentition suggests it had an omnivorous diet. Its striking dental autapomorphies, including development of a large hypocone, signal a shift of diet compared with other mystacinids, and may provide evidence of an adaptive radiation in feeding strategy in this group of noctilionoid bats

    Venire a Venezia: dodici percorsi e qualche incrocio

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    Author version made available following 12 month embargo from date of publication (12 October 2015) in accordance with Publisher copyright policy.An endemic and previously unknown lineage of shorebirds (Charadriiformes: Scolopaci) is described from early Miocene (19 16 Ma) deposits of New Zealand. Hakawai melvillei gen. et sp. nov. represents the first pre-Quaternary record of the clade in New Zealand and offers the earliest evidence of Australasian breeding for any member of the Scolopaci. Hakawai melvillei was a representative of the clade that comprises the South American seedsnipes (Thinocoridae) and the Australian Plains-wanderer (Pedionomidae), and presumed derived features of its postcranial skeleton indicate a sister taxon relationship to Australian pedionomids. Our findings reinforce that terrestrial adaptations in seedsnipes and the Plains-wanderer are convergent as previously proposed, and support an ancestral wading ecology for the clade. Although vicariance events may have contributed to the split between pedionomids and H. melvillei, the proposed sister taxon relationship between these taxa indicates that the split of this lineage fro

    Paleontología y Evolución de las Aves

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    Sheathbill-like birds (Charadriiformes: Chionoidea) from the Oligocene and Miocene of Australasia

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    The Chionoidea are a small, southern hemispheric shorebird clade that today includes the Magellanic Plover (Pluvianellidae) and two species of sheathbills (Chionidae). Here we describe the first fossil remains attributable to this group. The two newly described species, the early Miocene Neilus sansomae gen. et sp. nov. from New Zealand and the late Oligocene Chionoides australiensis gen. et sp. nov. from South Australia, are overall more similar to sheathbills, but the mosaic of characters shared with both Chionidae and Pluvianellidae preclude referral to either lineage. Attribution of fossils this age to these lineages also conflicts with divergence dates based on molecular data, as the split between the Magellanic Plover and sheathbills is hypothesised to be more recent. We therefore suggest that these Australasian, plover-size species represent the first record of stem-group taxa within Chionoidea. http://zoobank.org/urn:lsid:zoobank.org:pub:2A5A2FD1-C3B5-4BAB-88D8-5862FE9E797

    Genomic analyses of fairy and fulmar prions (Procellariidae: Pachyptila spp.) reveals parallel evolution of bill morphology, and multiple species

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    Prions are small petrels that are abundant around the Southern Ocean. Here we use mitochondrial DNA (COI and cytochrome b) and nuclear reduced representation sequencing (ddRADseq) to examine the relationships within and between fairy (Pachyptila turtur) and fulmar (P. crassirostris) prions from across their distributions. We found that neither species was recovered as monophyletic, and that at least three species were represented. Furthermore, we detected several genetic lineages that are also morphologically distinct occurring in near sympatry at two locations (Snares Islands and Chatham Islands). The factors that have driven diversification in the fairy/fulmar prion complex are unclear but may include philopatry, differences in foraging distribution during breeding, differences in non-breeding distributions and breeding habitat characteristics. The observed distribution of genetic variation in the fairy/fulmar prion complex is consistent with population expansion from ice-free Last Glacial Maximum refugia into previously glaciated areas
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