Small-Scale Geographic Variation in Antipredator Tactics of Garter Snakes

Goiran

et al. 2012

Biol J Linn Soc Lond

Populations of widespread species often differ in phenotypic traits, although rarely in such a dramatic fashion as revealed by research on turtle‐headed seasnakes (Emydocephalus annulatus). These snakes are highly philopatric, with mark–recapture studies showing that the interchange of individuals rarely occurs even between two adjacent bays (separated by < 1.2 km) in Noumea, New Caledonia. Data on > 500 field‐captured snakes from these two bays reveal significant differences between these two locations in snake morphology (mean body length, relative tail length, head shape), colour, ecology (body condition, growth rate, incidence of algal fouling), behaviour (antipredator tactics), and locomotor performance. For some traits, the disparity was very marked (e.g. mean swimming speeds differed by > 30%). The causal bases for these phenotypic divergences may involve founder effects, local adaptation, and phenotypic plasticity. The spatial divergence in phenotypic traits offers a cautionary tale both for researchers (sampling of only a few populations may fail to provide a valid overview of the morphology, performance, and behaviour of a species) and managers (loss of local populations may eliminate distinctive genetic variation). © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Section: Discussionmentioning

confidence: 99%

Phenotypic divergence between seasnake (Emydocephalus annulatus) populations from adjacent bays of the New Caledonian Lagoon

Goiran

et al. 2012

Biol J Linn Soc Lond

“…In our study population, adult males had an average 45 cm snout-vent length (SVL) and females an average of 60 cm. We worked in May 2004 at a large communal den containing >50 000 snakes 1·5 km north of Inwood in central southern Manitoba (50 ° 31·58 ′ N 97 ° 29·71 ′ W; see Shine et al . 2003a for more information on this den).…”

Section:    mentioning

confidence: 99%

“…Accordingly, snakes use such substrate‐deposited trails for many functions: for example, to locate sexual partners (Mason 1992), to avoid conspecifics (Shine et al . 2004) or predators (Shine et al . 2003a), to find overwintering dens (Gregory, Macartney & Larsen 1987), to locate hidden prey (Clark 2004), and to relocate prey that they have envenomated and then released (Chiszar et al .…”

Section: Introductionmentioning

confidence: 99%

“…Detailed laboratory studies have confirmed that this system allows snakes to accurately follow substratedeposited chemical trails left by conspecifics or prey animals. Accordingly, snakes use such substratedeposited trails for many functions: for example, to locate sexual partners (Mason 1992), to avoid conspecifics or predators (Shine et al . 2003a), to find overwintering dens (Gregory, Macartney & Larsen 1987), to locate hidden prey (Clark 2004), and to relocate prey that they have envenomated and then released (Chiszar et al .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mate location tactics in garter snakes: effects of rival males, interrupted trails and non‐pheromonal cues

et al. 2005

Self Cite

Summary 1.The ability to follow substrate-deposited scent trails using sophisticated vomeronasal abilities is a key feature of snake biology. However, previous research on this topic has derived mostly from a highly artificial test situation: captive snakes following continuous trails over structurally simple homogeneous substrates, in the absence of any other cues (e.g. visual or olfactory) either from the target of that search or from other snakes. 2. Our field experimental trials with Red-Sided Garter Snakes ( Thamnophis sirtalis parietalis ) at a communal den in Manitoba explored wider issues in mate location. 3. Males followed a female's trail less successfully if she had recently been followed by rival males, suggesting that trailing males obscured the cues left by the female. 4. Males that lost contact with a female's trail exhibited stereotyped, spatially extensive and prolonged circling behaviour centred on the last point at which the trail was detectable; in nature, this behaviour would maximize the male's ability to relocate a discontinuous trail. 5. Trail-following males switched from chemical to visual cues as soon as they were close to a female, enhancing speed but decreasing the accuracy of mate location (because males could distinguish between females and other males based on either visual or airborne olfactory cues). 6. Incorporating additional cues and broader spatial scales can clarify aspects of trail-following behaviour not evident from studies in small, highly simplified laboratory situations.

“…Antipredator responses offer excellent model systems for examining the causes of geographic variation in behavioural traits, because the link between effective predator defence and organismal fitness is clear (Shine et al . 2003a,b; Lind & Cresswell 2005).…”

Section: Introductionmentioning

confidence: 99%

Correlated geographic variation in predation risk and antipredator behaviour within a wide‐ranging snake species (Notechis scutatus, Elapidae)

Aubret

Michniewicz

Shine³

2010

Austral Ecology

Geographic variation in antipredator behaviour within wide-ranging species may be driven by both genetic and environmental influences. We quantified antipredator responses in neonatal (laboratory born, n = 555) and adult (field caught, n = 346) tiger snakes (Notechis scutatus) from 11 mainland and island sites in southern Australia. We used these data to test predictions from Bonnet et al.'s hypothesis that the vigour of antipredator responses in this species reflects behavioural plasticity (in turn, driven by an individual snake's exposure to predators during its lifetime) rather than by genetic variation in this trait. We used the number of predator taxa in each area as an index of predator risk. As predicted, adult snakes from predator-rich areas had more vigorous defensive responses when handled, whereas neonatal behaviour (although also variable among populations) was unrelated to predator species richness. Adult males bit more readily than adult females (as expected from the greater predation exposure of males during mate searching) but no such sex difference was evident in neonates. Although alternative models remain possible, our data are most consistent with the hypothesis that geographic divergence in antipredator tactics within this species primarily reflects developmentally plastic responses to local predation risk.