Hand-Wing Index as a surrogate for dispersal ability: the case of the Emberizoidea (Aves: Passeriformes) radiation

Abstract

Measuring the dispersal ability of birds is particularly challenging and thus researchers have relied on the extended use of morphological proxies as surrogates for such ability. However, few studies have tested the relationship between morphological proxies and other dispersal-related traits. In this study, we test the relationship of the most commonly used morphological proxy for dispersal—the Hand-Wing Index (HWI)—with traits highly associated with dispersal abilities, such as geographic range size, migratory behaviour and migratory distances. We used the Emberizoidea superfamily to evaluate these relationships and measured the HWI of 2520 individuals from 431 species (almost half of all the species in the superfamily). We first estimated the phylogenetic signal of HWI and searched for the best evolutionary model to explain its variation. We then performed PGLS analyses to assess the relationships between HWI and dispersal abilities. Our results showed that HWI has a strong phylogenetic signal and is positively related to dispersal abilities. Our findings support the use of HWI as a viable morphological proxy for dispersal in birds.

Determinants of natal dispersal distances in North American birds

“…We did not find an association between dispersal distances and geographic range size. Despite clear theoretical expectations and some empirical evidence (Alzate & Onstein, 2022;Arango et al, 2022;Capurucho et al, 2020;Laube et al, 2012;Lester et al, 2007), we found that natal dispersal distances of widespread species were similar to those of range-restricted species. A potential correlation between geographic range size and dispersal distances may be dampened by the negative correlation between dispersal distances and population size, as widespread species tend to be more abundant (Bock & Ricklefs, 1983;Brown & Munger, 1985) and less dispersive (Claramunt, 2021, this study).…”

Amazonian birds in more dynamic habitats have less population genetic structure and higher gene flow

“…Targeted searches along this river and in the intervening regions did not find populations of this species, supporting the hypothesis that this was a wandering individual (Ingels et al, 2012). Proxy measures like the HWI probably remain powerful predictors of dispersal potential generally, as evidenced in recent comparative (Arango et al, 2022;Claramunt, 2021;Dawideit et al, 2009;Sheard et al, 2020;Weeks et al, 2022) and experimental approaches (Naka et al, 2022) but may not be useful in all habitats or for all species, or when other historical or ecological variables (see for example Capurucho et al, 2020) overcome their effect. Many of these potential ecological variables, such as generation time and reproductive behaviour, are not available for many Amazonian species, highlighting the need for additional natural history data.…”

Spatio‐temporal integrated Bayesian species distribution models reveal lack of broad relationships between traits and range shifts

“…Although a small effect, HWI tended to be negatively associated with range expansions. Previous work has identified HWI as being strongly positively correlated with dispersal ability across many bird taxa (Arango et al, 2022), meaning we would have expected to see more expansions as HWI increases. However, this effect may be confounded by the reproductive strategies of smaller birds with lower HWI.…”