Landscape factors and allochthonous congeneric species influence Callithrix aurita occurrence in Brazilian Atlantic Forest remnants

Abstract

The buffy-tufted-ear marmoset (Callithrix aurita) is a small primate endemic to the Brazilian Atlantic Forest biome, and one of the 25 most endangered primates in the world, due to fragmentation, loss of habitat, and invasion by allochthonous Callithrix species. Using occurrence data for C. aurita from published data papers, we employed model selection using Akaike Information Criterion corrected for small samples and cumulative AICc weight (w ₊) to evaluate whether fragment size, distance to fragments with allochthonous species, altitude, connectivity, and surrounding matrices influence the occurrence of C. aurita within its distributional range. Distance to fragments with C. jacchus (w ₊ = 0.94) and nonvegetated areas (w ₊ = 0.59) correlated negatively with C. aurita occurrence. Conversely, the percentage of agriculture and pasture mosaic (w ₊ = 0.61) and the percentage of savanna formation (w ₊ = 0.59) in the surrounding matrix correlated positively with C. aurita occurrence. The findings indicate that C. aurita is isolated in forest fragments surrounded by potentially inhospitable matrices, along with proximity of a more generalist and invasive species, thereby increasing the possibility of introgressive hybridization. The findings also highlighted the importance of landscape elements and allochthonous congeneric species for C. aurita conservation, besides indicating urgency for allochthonous species management. Finally, the approach used here can be applied to improve conservation studies of other endangered species, such as C. flaviceps, which is also endemic to the Brazilian Atlantic Forest and faces the same challenges.

Keywords: Callithrix aurita; alien species; biodiversity hotspot; land use and cover; species management; surrounding matrix.

FIGURE 1

Map of the study area (hatched) delimited by the distribution of Callithrix aurita in Southeast Brazil (adapted from Melo et al., 2021). The original distribution areas of the allochthonous congeneric species are represented by the other filled areas.

FIGURE 2

Map of land cover types found in the study area (distribution of Callithrix aurita adapted from Melo et al., 2021) relating to the year 2019, acquired on the Mapbiomas platform (MAPBIOMAS, 2020).

FIGURE 3

Map of records for Callithrix aurita (black ball), C. penicillata (lozenge), C. jacchus (triangle), and control fragments (without the confirmed presence of C. aurita white ball), located within the study area.

FIGURE 4

Effects of minimum distance to fragments with Callithrix jacchus (a), and percentages of agriculture and pasture mosaic (b), nonvegetated (c), and savanna formation (d) in the surrounding matrix, on the probability of C. aurita occurrence in forest fragments that occur within the species' distribution in Southeast Brazil. Black dots represent fragments with confirmed occurrence of C. aurita while gray dots represent those without (control). The gray range represents the confidence intervals.