Climatic niche divergence or conservatism? Environmental niches and range limits in ecologically similar damselflies

Abstract

The factors that determine species' range limits are of central interest to biologists. One particularly interesting group comprises odonates (dragonflies and damselflies), which show large differences in secondary sexual traits and respond quickly to climatic factors, but often have minor interspecific niche differences, challenging models of niche-based species coexistence. We quantified the environmental niches at two geographic scales to understand the ecological causes of northern range limits and the coexistence of two congeneric damselflies (Calopteryx splendens and C. virgo). Using environmental niche modeling, we quantified niche divergence first across the whole geographic range in Fennoscandia, and second only in the sympatric part of this range. We found evidence for interspecific divergence along the environmental axes of temperature and precipitation across the northern range in Fennoscandia, suggesting that adaptation to colder and wetter climate might have allowed C. virgo to expand farther north than C. splendens. However, in the sympatric zone in southern Fennoscandia we found only negligible and nonsignificant niche differences. Minor niche differences in sympatry lead to frequent encounters and intense interspecific sexual interactions at the local scale of populations. Nevertheless, niche differences across Fennoscandia suggest that species differences in physiological tolerances limit range expansions northward, and that current and future climate could have large effects on the distributional ranges of these and ecologically similar insects.

Ecological niche differentiation and taxonomic distinction between Eremias strauchi strauchi and Eremias strauchi kopetdaghica (Squamata: Lacertidae) on the Iranian Plateau based on ecological niche modeling

“…Based on these results, there is significant niche differentiation between E. s. strauchi and E. s. kopetdaghica. Ecological niche divergence, in the present study, in an allopatric condition has been inferred to represent ecological speciation (Rundle & Nosil 2005;Wellenreuther et al 2012). Our results confirm the taxonomic suggestion of Rastegar-Pouyani et al (2015) that both subspecies can be upgraded to the species level.…”

“…The variable with the highest gain adds the most useful information to the model, while the variable with the lowest gain importance has little effect on the model. Finally, we extracted the environmental suitability index generated by the niche model and regressed it against latitude and longitude to evaluate their effects on niche differences (Wellenreuther et al 2012). …”

Sex differences in developmental plasticity and canalization shape population divergence in mate preferences

“…Our results strongly suggest that sex differences in developmental plasticity and canalization jointly influence population divergence in mate preferences and variation in local responses to heterospecifics. These sex differences in learning, plasticity and canalization are likely to play a crucial role in population divergence and speciation processes, particularly in damselflies and other odonates, where ecological speciation through niche differentiation plays a minor role [25,26] compared with the stronger diversifying effects of social selection, sexual selection and mating conflicts between males and females [27][28][29].…”

“…These features of the ecology and natural history of demoiselles make them excellent study organisms to investigate how sex differences in developmental plasticity and learning might affect local adaptation and population divergence in the presence or absence of conspecifics and in the face of gene flow. As these demoiselles and other odonates (dragonflies and damselflies) often show weak ecological differentiation between species [25,26], they challenge models of ecological speciation and point to non-ecological speciation mechanisms through social selection, sexual selection, sexual conflict and/or learning [27][28][29][30].…”

The effect of male-male competition and ornament size on mean and variance of courtship intensity towards heterospecific and conspecific females

“…The species diverged five million years ago and are not considered as sister species (Dumont et al 2005). There seems to be no significant niche divergence between the species when they are sympatric in Scandinavia (Wellenreuther et al 2012). And at least in Finland, C. splendens is almost always sympatric with C. virgo ) but C. virgo can occur in allopatric populations.…”