Contrasting patterns of altitudinal distribution between parasitoid wasps of the subfamilies Braconinae and Doryctinae (Hymenoptera: Braconidae)

Abstract

Many tropical organisms have narrow altitudinal ranges and therefore may be especially vulnerable to climate change. Parasitoid wasps are no exception, so baseline knowledge about their vulnerability to rising temperatures needs to include analyses of their distributional ranges along elevational gradients. Using museum collections of the parasitoid subfamilies Braconinae and Doryctinae (Hymenoptera: Braconidae) from Costa Rica, we tested two alternative hypotheses explaining altitudinal distributions of communities: (i) the Mid‐domain effect, which states that species diversity peaks at middle elevations as a result of species’ random distributions; and (ii) Rapoport's effect, which predicts that species diversity should monotonically decrease with increasing elevation. We found that for the Doryctinae, species diversity decreased monotonically with elevation, while the Braconinae showed two peaks. Species altitudinal ranges increased with elevation in the Doryctinae, as predicted by Rapoport's effect, but not so in the Braconinae. Neither of the subfamilies’ distributions fit the prediction of the Mid‐domain effect. The richness peak at low elevations displayed by the Braconinae and Doryctinae matches the distribution of wood‐boring beetles, which are potential hosts for both taxa. The second peak described in the Braconinae at middle elevations may reflect either better access or higher availability of potential hosts in the Diptera and Lepidoptera at those elevations. Because species in the Doryctinae, on average, had altitudinal ranges that were broader and lower in elevation than species in the Braconinae, our results suggest that species in the Doryctinae might have greater resilience to future temperature increases.

Two new species and distribution records for the genus Bohayella Belokobylskij, 1987 from Costa Rica (Hymenoptera, Braconidae, Cardiochilinae)

“…The elevation of Costa Rica ranges from sea level to 3,819 m (Hanson and Gauld 1995). If additional sampling is conducted across the country and more species of Bohayella are discovered, altitudinal distribution patterns of members of Costa Rican Bohayella can be investigated in the future (e.g., Aguirre et al 2018).…”

Uncovering the Brazilian Orthocentrinae (Hymenoptera: Ichneumonidae) fauna: high diversity at high elevation

“…Although criticisms have been made of Rapoport's rule and on the methods for its evaluation, the underlying mechanism seems to be valid and received good support recently (e.g., Chan et al 2016), even when species ranges do not follow predictions due to complex climate gradients (Pintor et al 2015). This and the fact that mountain passes are higher in the tropics (Janzen 1967;Sheldon et al 2018) may be important factors that could lead to observations confirming larger elevational ranges at higher elevations in tropical mountains, as observed for braconids (Aguirre et al 2018). This is an extremely relevant consideration for conservation because tropical lowlands could harbour the highest diversity and concurrently suffer the greatest impacts.…”

“…Local intensive faunistic assessments of the Ichneumonoidea along elevational gradients have been helpful in understanding diversity patterns in this group, which most commonly peaks at mid-elevations in tropical mountains (e.g., van Noort 2004;Peck et al 2008;Veijalainen et al 2014b), a pattern predicted by the "mid-domain effect" (Colwell and Lees 2000). High diversity in lowlands has also been reported (Sääksjärvi et al 2004;Aguirre et al 2018). Richness peaks at low elevations may be predicted by Rapoport's rule, as a result of increasing range size with increasing elevations or latitudes (Stevens 1992).…”

“…According to the rule, both for latitude and elevation, the lower bands would present higher species richness as a result of narrower ranges (explained by their physiological constrain) of the species evolving in warmer and more stable climate. Despite these general patterns, some degree of idiosyncrasy is expected, and richness peaks may vary depending on the group studied (e.g., Gauld 1988Gauld , 1991Gauld , 1997Gauld , 2000Gauld et al 2002;Aguirre et al 2018).…”