However, more than a century after Darwin, it remains unclear why restricted dispersal has evolved repeatedly in island organisms, particularly in species that have retained the capacity for dispersive movement.Įxplaining the origins of variation in the dispersal abilities of animals be it on islands or continents is not simple. Flightlessness is an extreme post-colonization phenotypic manifestation that inevitably leads to reduced dispersal ability in such organisms. For instance, among Charles Darwin's most remarkable observations during his voyages were repeated accounts of flightless birds and beetles on islands. However, it is the post-colonization dispersal tendencies of individuals, or alternatively their site fidelity, that strongly influences the evolutionary and ecological dynamics observed in island biota. intraspecific niche partitioning) to constrain dispersal in island species.Īstounding feats of long-distance dispersal often explain how animals colonize remote oceanic islands, a fundamental process in island biogeography. via benefits of spatial philopatry and increased costs of dispersal) alongside use of dispersal-compensating traits (e.g. We suggest that direct selection restricts movement capacity (e.g. indices of risk for inbreeding, kin and intraspecific competition, and low habitat quality) that consequently reduced survival of resident individuals. Importantly, lizard site-fidelity was insensitive to common agents of dispersal evolution (i.e.
In the Komodo dragon, concordant results from telemetry, simulations, experimental translocations, mark-recapture, and gene flow studies indicated that despite impressive physical and sensory capabilities for long-distance movement, Komodo dragons exhibited near complete dispersal restriction: individuals rarely moved beyond the valleys they were born/captured in. Here, we combined observational and experimental analyses of an island lizard, the Komodo dragon ( Varanus komodoensis, the world's largest lizard), to provide evidence for the actions of multiple processes that could contribute to island dispersal loss.
natural selection or spatial sorting) processes may be involved, and no study has yet convincingly distinguished between these alternatives. relaxed selection or island syndromes) and direct (e.g. This is because selection via, both indirect (e.g. Loss of dispersal typifies island biotas, but the selective processes driving this phenomenon remain contentious.
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