Heterospecific Aggression and Adaptive Divergence in Brook Stickleback (Culaea Inconstans)

Abstract

Agonistic behavior between heterospecifics, in which individuals of one species attack another, may cause a subordinate species to shift resource or habitat use. Subsequent evolutionary responses to selection may mimic shifts expected under ecological character displacement, but with no role played by exploitative competition. Alternatively, aggressive behavior can evolve when fitness is improved by excluding members of a coexisting species from a defendable resource through interference. We tested whether heterospecific agonistic behavior has evolved in brook stickleback (Culaea inconstans) by comparing replicate allopatric populations to those sympatric with ninespine stickleback (Pungitius pungitius). We also tested for heritable variation in heterospecific aggressive behavior by rearing family groups in a common environment. Allopatric populations of brook stickleback were more aggressive than ninespine stickleback, suggesting that pre-existing aggression in brook stickleback contributed to niche shifts by ninespine stickleback. In addition, sympatric adult brook stickleback were more aggressive toward ninespine stickleback than brook stickleback from allopatric populations. Overt heterospecific aggressive behaviors were heritable, and aggression in juvenile brook stickleback increased with age in sympatric but not in allopatric populations reared in a common environment. Brook stickleback have evolved increased aggression when they coexist with ninespine stickleback. These stickleback communities have been structured by both evolved and pre-existing variation in heterospecific aggressive behavior in brook stickleback.

Experimental evidence for asymmetric mate preference and aggression: behavioral interactions in a woodrat (Neotoma) hybrid zone

“…The pattern we observed in our trials is consistent with one wherein both species of woodrats in sympatry selectively benefit from increased aggression, perhaps because it increases their ability to compete for optimal den sites, especially the relatively rare boulder den sites [20]. As suggested by Peiman and Robinson [37,38], the pattern should be more pronounced with the dominant species, as we observed in interactions with larger N. bryanti males (Figure 4E).…”

Male-Male Competition as a Force in Evolutionary Diversification: Evidence in Haplochromine Cichlid Fish

“…Agonistic character displacement has received limited attention (e.g., [21, 22]), despite the fact that these ideas date back to the 60s [23, 24]. It can take place in a range of different traits that affect the rate, intensity, and outcome of interference competition [16].…”

Intra- and interspecific aggression do not modulate androgen levels in dusky gregories, yet male aggression is reduced by an androgen blocker

“…Scientists discussing social behavior typically refer to intraspecific interactions (Blumstein et al, 2010), and as an example, a recent textbook on the topic did not mention a single case of interspecific interactions (Székely et al, 2010). This omission may look surprising since organisms are sometimes embedded in a heterogeneous network where interspecific interactions are frequent and exert profound effects on fitness (Bshary, 2001;Peiman and Robinson, 2007). In addition, intra-and interspecific behaviors can be classified largely along the same line depending on their effect on the direct reproductive fitness of the different partners.…”