![]() Dragonfly-lake species also adapted biochemically in that their muscle tissue have greater arginine kinase activity, which is the enzyme that recharges ATP to be used by muscle. Dragonfly-lake larvae also evolved greater muscle mass in their abdomens, and they evolved to beat their abdomens faster as they swim. These lamellae evolved to be larger in dragonfly-lake species. Swimming larvae generate thrust by waving their abdomens and pushing their caudal lamellae like a boat paddle through the water. Many different phenotypic traits that influence swimming speed evolved to generate this increase in swimming performance. Relationship between the percent of individuals that swim in swimming trials versus arginine kinase specific activity for multiple Enallagma species in dragonfly lakes and Northern- and Southern-clade species in fish lakes. Evolving to swim faster to evade attacking dragonflies is therefore a critical adaptation to invading this new habitat. The ancestral Enallagma species were in fish lakes, and lineages have only recently invaded dragonfly lakes. Evolutionary analyses have shown that these differences between fish and dragonfly-lake species are evolved differences, which means that evolving faster swimming is an adaptation to living with large dragonflies. Species that live in dragonfly lakes swim much faster than species that live with fish. These differences in swimming as an escape behavior between species has also evolved to make a large difference in swimming performance between fish- and dragonfly-lake species in both genera. Different symbols in each category are different species. The three regression lines are for each of these three groups. Filled symbols are larvae of dragonfly-lake species, open symbols are larvae of Northern-clade fish-lake species, and line symbols are larvae of Southern-clade fish-lake species. Swimming speed (cm/sec) of larvae of multiple Enallagma species in three major groups. However, damselflies in fish lakes most frequently do not move when attacked by a predator in effect, they freeze when a predator is near and stay motionless until the predator moves away, presumably in hopes of the predator not seeing it. Consistent with this, damselflies that live in dragonfly lakes most frequently swim away from an attacking predator. In contrast, fish move much faster than damselfly larvae, and so a damselfly larva has absolutely not chance of evading an attacking fish by swimming. This means that a damselfly attacked by a dragonfly has some likelihood of escaping if it swims away from the dragonfly. Dragonflies and damselflies can move at relatively similiar speeds. Therefore, these two lakes will hereafter be identified as dragonfly lakes and fish lakes, respectively. Large dragonflies are the main predators of damselfly larvae in fishless lakes, and fish are the main predators of damselfly larave in fish lakes. Other species in each lake type show similar behaviors. dryas live in vernal ponds with no predators. congener live in temporary and permanent dragonfly ponds. Enallagma vesperum and Lestes vigilas live in fish lakes. Adaptation to Predators Frequency of three behaviors (no movement, walk away, swim away) expressed by representative damselfly species that live in the four main lake types. Phylogenetic studies using morphological characters and mitochondrial DNA data indicate that fish lakes were the ancestral habitat for Enallagma, and three separate lineages of Enallagma have invaded dragonfly-dominated lakes. ![]() In addition to the mechanisms that presently structure these communities, we have explored how the abilities of damselfly species to evade predators and acquire and utilize resources have been shaped by evolutionary processes in the the various species that occupy different lake types that are defined by the top predator in each. Damselfly Adaptation to the Ecological Conditions Defining Various Habitats
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