Niche conservatism of Aedes albopictus and Aedes aegypti - two mosquito species with different invasion histories

Abstract

Biological invasions have been associated with niche changes; however, their occurrence is still debated. We assess whether climatic niches between native and non-native ranges have changed during the invasion process using two globally spread mosquitoes as model species, Aedes albopictus and Aedes aegypti. Considering the different time spans since their invasions (>300 vs. 30–40 years), niche changes were expected to be more likely for Ae. aegypti than for Ae. albopictus. We used temperature and precipitation variables as descriptors for the realized climatic niches and different niche metrics to detect niche dynamics in the native and non-native ranges. High niche stability, therefore, no niche expansion but niche conservatism was revealed for both species. High niche unfilling for Ae. albopictus indicates a great potential for further expansion. Highest niche occupancies in non-native ranges occurred either under more temperate (North America, Europe) or tropical conditions (South America, Africa). Aedes aegypti has been able to fill its native climatic niche in the non-native ranges, with very low unfilling. Our results challenge the assumption of rapid evolutionary change of climatic niches as a requirement for global invasions but support the use of native range-based niche models to project future invasion risk on a large scale.

Predicting the success of an invader: Niche shift versus niche conservatism

“…albopictus does not (yet) occupy all the suitable areas available in Europe, which could be related to the short time since introduction in Europe (40 years). This result is congruent with those found by Cunze et al () and suggests that niche conservatism is the typical pattern in Ae. albopictus invasion process.…”

“…Here, we compared the environmental niches of European introduced populations with the one of their US (from ancestral Japan origin that was included in the analysis) and Chinese sources (Sherpa, Blum, Capblancq, et al, ). The comparison of niches in reduced environmental space revealed that the two source populations for the European invasion have broad, different but overlapping environmental niches (Figure a), as previously reported (Cunze et al, ; Medley, ). The distribution of European populations in this space reveals niche differences between primarily introduced populations and their source populations, with centroids shift related to winter climate for Albania and human pressure for North Italy (Figure a).…”

“…We confirm that niche conservatism is the typical pattern in Ae. albopictus invasion process (Cunze et al, ), which seems to be dominant among invasions in similar climate areas (Guisan et al, ). This result together with the apparent low conservatism between the environmental niches in Europe and Japan suggests that invasive populations retain the niche of their US source where the niche shift occurred, as Ae.…”

“…albopictus has not directly been introduced in Europe from Japan (Sherpa, Blum, Capblancq, et al, ). However, niche differences observed between US populations and their sources (Figure ), or the native Asian range (Medley, ), are probably due to niche unfilling (Cunze et al, ). Despite niche conservatism characterizes the European and North American invasions, the rapid evolution of traits (Europe: present study; Kreß et al, , United States: Urbanski et al, ; Armbruster, ; Medley, Westby, & Jenkins, ) suggests genetic shift from standing variation in response to new selective pressures encountered in the invaded area.…”

Cold adaptation in the Asian tiger mosquito's native range precedes its invasion success in temperate regions

“…Furthermore, there is no clear indication for niche expansion that would have required adaptive evolution in temperate invaded areas (Cunze et al. ). Demonstrating that adaptation occurred within the native range would shed light into the contribution of preadaptation in the invasion process (Hufbauer et al.…”