Increased genetic differentiation in a specialist versus a generalist bee: implications for conservation

Abstract

Oligolectic bees are specialists that collect pollen from one or a few closely related species of plants, while polylectic bees are generalists that collect pollen from both related and unrelated species of plants. Because of their more restricted range of floral hosts, it is expected that specialists persist in more isolated populations than do generalists. We present data on the population structure of two closely related bee species sampled from a super abundant floral host in the southern Atacama Desert. Pairwise comparisons of population subdivision over identical distances revealed that the specialist bee had significantly more differentiated populations in comparison to the generalist. Further, populations of the specialist had significantly less genetic variation, measured as observed and expected heterozgyosity, than those of the generalist. Our data support the hypothesis of decreased gene flow among populations of the specialist bee even at equivalent geographic distances. The resulting reductions in effective population size for specialists make them particularly prone to extinction due to both demographic and genetic reasons. Our findings have important implications for the conservation of bees and other specialist insects.

Conservation ecology of bees: populations, species and communities

“…This variability parallels that found in other animal groups (e.g. Vandergast and Gillespe, 2004) and indicates that responses may differ depending on life history and other speciesspecific attributes, such as dispersal ability and floral specificity (Cane and Tepedino, 2001;Zayed et al, 2005). A further complication occurs when the response of a taxon is obscured by the composition of the surrounding matrix of habitats and its influence on the availability of floral and nesting resources (Eltz et al, 2002;Williams N.M. and Kremen, 2007).…”

Estudio de microsatélites en las abejas sin aguijón Melipona colimana y M. beecheii de Mesoamérica

“…Lopes et al (2010) observaron un descenso de la heterocigosidad en M. rufiventris y M. mondury a causa del reducido número de colonias encontradas como consecuencia de la destrucción y fragmentación de sus ecosistemas naturales. Otros estudios revelaron que la fragmentación de los hábitats afecta en mayor medida a los individuos especialistas que a los generalistas (Kitahara y Fujii, 1994), como es el caso de las abejas sin aguijón (Zayed et al, 2005). En el caso de M. colimana, al no ser una especie explotada para la producción, sus poblaciones están sujetas a los efectos de la deforestación y de la destrucción de su hábitat.…”

Diversity and conservation status of native Australian bees

“…Of major concern is the absence of basic information about the biology of the bee fauna. Although the majority of species are polylectic, it is the significant minority of oligolectic species that are most under threat (Zayed et al, 2005;Zayed, 2009) and most likely to have difficulty adapting to new hosts (Praz et al, 2008). Many oligolectic species may remain undiscovered.…”