Effects of forest fragmentation on the morphological and genetic structure of a dispersal-limited, endangered bird species

Abstract

Citation: Hermes C, Döpper A, Schaefer MH, Segelbacher G (2016) Effects of forest fragmentation on the morphological and genetic structure of a dispersal-limited, endangered bird species. Nature Conservation 16: 39-58. doi: 10.3897/ natureconservation. 16.10905 Abstract Throughout the tropics, pristine forests disappear at an alarming pace. This presents a severe threat to forest-dependent species. Especially dispersal-limited understory birds are affected by forest loss. We here explored the effects of habitat fragmentation on the genetic structure and the morphology of the Ecuadorian Tapaculo (Scytalopus robbinsi). This bird occurs only in a small range in the premontane cloud forests of southwestern Ecuador. The global population size is declining rapidly due to habitat loss and is currently estimated at only 3000 mature individuals. We caught a total of 28 Ecuadorian Tapaculos in forests of varying size in an area of about 40 km². From each bird, we took morphological measurements and a blood sample. This was used to develop a set of 10 species-specific microsatellite primers for genetic analysis and we found that the Ecuadorian Tapaculos display high levels of genetic diversity. Additionally, we identified dispersal corridors for the species across the landscape using a least-cost path analysis. Notably, we found that wing shape is related to forest size. Individuals in smaller fragments show adaptations of the wing morphology to enhanced mobility and better flight capacity. Our results suggest that the Ecuadorian Tapaculo may rapidly adapt its morphology to the level of habitat fragmentation. This potential can possibly mitigate the risk of local extinctions of the species due to human-caused forest loss and fragmentation.

Variation in fine‐scale genetic structure and local dispersal patterns between peripheral populations of a South American passerine bird

“…Studies examining fine-scale genetic structure in birds have been carried out at different spatial scales, depending on the underlying factors and hypotheses being considered. Several studies focusing on the influence of habitat heterogeneity on gene flow have investigated spatial variation at the landscape level (>10 km), and detected genetic differences among populations of species that showed high habitat specificity (e.g., Browne et al, 2008;Walsh, Kovach, Babbit, & O′Brien, 2012;Woltmann, Kreiser, & Sherry, 2012) or sex-biased and/ or restricted dispersal (e.g., Coulon, Fitzpatrick, Bowman, & Lovette, 2010;Coulon et al, 2008;Hermes, Döpper, Schaefer, & Segelbacher, 2016;Pierson et al, 2010). On the other hand, studies aiming at linking spatial patterns to complex social interactions have assessed genetic variation at a smaller geographic scale (<5 km), and found finescale genetic structure within populations of cooperatively breeding and lekking birds (e.g., Beck et al, 2008;Double, Peakall, Beck, & Cockburn, 2005;Van Dijk et al, 2015).…”

“…Dispersal behavior can also vary spatially due to local differences in habitat heterogeneity, demographic factors, and social interactions (Bowler & Benton, 2005;Cote & Clobert, 2012), and hence, intraspecific variation in dispersal and in population spatial structure is expected under distinct environmental contexts (see Matthysen, 2012). As variability in habitat patchiness and population density can affect local gene flow (Walsh et al, 2012), distinct patterns of finescale genetic structure between breeding populations are likely to occur (Hermes et al, 2016;Lee et al, 2010;Stow, Sunnucks, Briscoe, & Gardner, 2001). However, the mechanisms behind within-species variation in dispersal patterns and in microgeographic genetic structure and the effects of varying life histories or contrasting ecological conditions remain relatively poorly understood (Le Galliard, Massot, & Clobert, 2012;Van Dijk et al, 2015).…”

Coupling movement and landscape ecology for animal conservation in production landscapes

“…At high levels of isolation, dispersal traits can be selected against due to high rates of mortality in the matrix, whereas dispersal and reproduction theoretically should be higher at lower levels of isolation [54], and empirical studies provide some support for this [60]. For instance, forest fragmentation affected the wing biomechanics of the Ecuadorian tapaculo (Scytalopus robbinsi) [61]. Birds in small fragments had narrower wings, which may have allowed them to colonize these fragments, whereas birds in larger fragments had rounder wings less suited for longer distance dispersal [61].…”

“…For instance, forest fragmentation affected the wing biomechanics of the Ecuadorian tapaculo (Scytalopus robbinsi) [61]. Birds in small fragments had narrower wings, which may have allowed them to colonize these fragments, whereas birds in larger fragments had rounder wings less suited for longer distance dispersal [61]. Further examples of altered motion capacity in response to landscape change include damselflies (Calopteryx maculata) with larger wings [62], North American birds with narrower wings [63] and butterflies with lower wing load ratios (a proxy for flight capacity) [20].…”

“…In this section, we demonstrate how altered resource availability can affect foraging decisions and home range movement, and how external factors influence decision-making during different stages of dispersal. movement path -tortuosity/directionality [12,44,45,46,52] -home range size and overlap [3,11,37] -foraging distance [17,36,37] -dispersal rate, timing and distance [3,4,5,14,56,57,58,78] motion capacity -habitat loss and fragmentation [3,20,58,61] -food availability [11] -physical barriers [8,19] -predation [3,78] navigation capacity -habitat loss and fragmentation [12,41,44,45,46,52,53] fitness [18,20,37,58] internal state -habitat loss and fragmentation [17,18,36,37,38,41] -competition/inbreeding [5,…”