What has happened to the females? Population trends in the Aesculapian snake at its northern range limit

Kurek, Katarzyna; Ćmiel, Adam M.; Bury, Stanisław; Zając, Bartłomiej; Najberek, Kamil; Babiasz, Ryszard; Musilová, Radka; Baś, Grzegorz; Najbar, Bartłomiej

doi:10.1016/j.gecco.2019.e00550

Cited by 6 publications

(8 citation statements)

References 31 publications

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“…Speci cally, limited resource availability may decrease postpartum survivorship (Sperry and Weatherhead 2009), while high movement rate during oviposition additionally elevates road mortality (Bonnet et al 1999). Our results corroborate previous ndings on snakes Kurek et al 2019) indicating a rather asymmetric response of both sexes towards environmental change.…”

Section: Discussionsupporting

confidence: 90%

“…This may result from an increased number of males or a reduced share of females. However, we perceive the latter as more likely in view of the welldocumented decline in snake populations world-wide (Reading et al 2010), which may be preceded by female loss (Kurek et al 2019). Both the reduced body size and lower share of females may represent an outcome of similar factors and drive future dynamics of the population.…”

Section: Discussionmentioning

confidence: 82%

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Decline in Body Size and Female Fraction in the Grass Snake (Natrix Natrix, Linnaeus 1758) Population After 40 Years (Southern Poland)

Bury

Zając

Okarma

et al. 2021

Preprint

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Depletion of free-living populations is often associated with changes in fitness-related traits, e.g. body size. Ongoing decrease in body size has been reported in most vertebrates, but reptiles remain understudied. Moreover, sexual size dimorphism, commonly observed in reptiles, indicates that environmental pressures on body size may appear sex-specific. This can also result in shifts in sex ratio, an aspect even less studied. We investigated body size and sex ratio in population of grass snake (Natrix natrix) surveyed over 40 years ago in comparison with the current state. We found that both sexes express similar magnitude in body size decline. The current sex ratio does not deviate from 1:1, while in the past females outnumbered males. The observed changes are likely an outcome of several non-mutually exclusive factors. In the studied area an increase in road traffic, human presence and a drop in prey availability has been documented. Both factors may exert higher pressure on larger individuals, particularly females, due to their high costs of reproduction. Recorded here increase in ambient temperatures and summer duration, may additionally enhance the mortality risk and resource requirements. Shifts in body size and sex ratio can catalyze further declines in abundance and reproductive potential of the population.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 82%

Decline in Body Size and Female Fraction in the Grass Snake (Natrix Natrix, Linnaeus 1758) Population After 40 Years (Southern Poland)

Bury

Zając

Okarma

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…This may result from an increased number of males or a reduced share of females. However, we perceive the latter as more likely in view of the well-documented decline in snake populations worldwide (Reading et al 2010 ), which may be preceded by female loss (Kurek et al 2019 ). Both the reduced body size and lower share of females may represent an outcome of similar factors and drive future dynamics of the population.…”

Section: Discussionmentioning

confidence: 86%

“…Therefore, it is crucial to recognize patterns associated with the decline process to predict its future dynamics. A drop in population numbers can be predicted to be preceded by alteration in population structure and individuals’ properties related to survival and reproduction (Stephens et al 1999 ; Kurek et al 2019 ). However, long-term data to investigate such changes are still relatively uncommon, especially for ectotherm vertebrates.…”

Section: Introductionmentioning

confidence: 99%

“…At the whole population level, size-biased pressure can result in changes of sex ratio. Temporal deviations in sex ratio have recently been recognized as likely to precede population decline (Kurek et al 2019 ), but long-term changes in sex ratio represent an aspect even less recognized. It is therefore premature to conclude about the global patterns of the temporal changes in body size and sex ratio, but such data is critical to gain insight into the patterns associated with the global decline of reptile populations.…”

Section: Introductionmentioning

confidence: 99%

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Decline in body size and female fraction in the grass snake (Natrix natrix, Linnaeus 1758) population after 40 years (Southern Poland)

Bury

Zając

Okarma

et al. 2021

Environ Sci Pollut Res

Self Cite

View full text Add to dashboard Cite

Depletion of free-living populations is often associated with changes in fitness-related traits, e.g., body size. Ongoing decrease in body size has been reported in most vertebrates, but reptiles remain understudied. Moreover, sexual size dimorphism, commonly observed in reptiles, indicates that environmental pressures on body size may appear sex-specific. This can also result in shifts in sex ratio, an aspect even less studied. We investigated body size and sex ratio in population of grass snake (Natrix natrix) surveyed over 40 years ago in comparison with the current state. We found that both sexes express similar magnitude in body size decline. The current sex ratio does not deviate from 1:1, while in the past, females outnumbered males. The observed changes are likely an outcome of several non-mutually exclusive factors. In the studied area, an increase in road traffic and human presence and a drop in prey availability have been documented. Both factors may exert higher pressure on larger individuals, particularly females, due to their high costs of reproduction. It is recorded here that increase in ambient temperatures and summer duration may additionally enhance the mortality risk and resource requirements. Shifts in body size and sex ratio can catalyze further declines in abundance and reproductive potential of the population.

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Evolution of parthenogenetic reproduction in Caucasian rock lizards: A review

et al. 2022

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Despite numerous works devoted to hybrid origin of parthenogenesis in reptiles, the causes of hybridization between different species, resulting in the origin of parthenogenetic forms, remain uncertain. Recent studies demonstrate that sexual species considered parental to parthenogenetic rock lizards (Darevskia spp) avoid interspecific mating in the secondary overlap areas. A specific combination of environmental factors during last glaciation period was critical for ectotherms, which led to a change in their distribution and sex ratio. Biased population structure (e.g., male bias) and limited available distributional range favoured the deviation of reproductive behaviour when species switched to interspecific mates. To date, at least seven diploid parthenogenetic species of rock lizards (Darevskia, Lacertidae) originated through interspecific hybridization in the past. The cytogenetic specifics of meiosis, in particular the weak checkpoints of prophase I, may have allowed the formation of hybrid karyotypes in rock lizards. Hybridization and polyploidization are two important evolutionary forces in the genus Darevskia. At present, throughout backcrossing between parthenogenetic and parental species, the triploid and tetraploid hybrid individuals appear annually, but no triploid species found among Darevskia spp on current stage of evolution. The speciation by hybridization with the long-term stage of diploid parthenogenetic species, non-distorted meiosis, together with the high ecological plasticity of Caucasian rock lizards provide us with a new model for considering the pathways and persistence of the evolution of parthenogenesis in vertebrates.

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What has happened to the females? Population trends in the Aesculapian snake at its northern range limit

Cited by 6 publications

References 31 publications

Decline in Body Size and Female Fraction in the Grass Snake (Natrix Natrix, Linnaeus 1758) Population After 40 Years (Southern Poland)

Decline in Body Size and Female Fraction in the Grass Snake (Natrix Natrix, Linnaeus 1758) Population After 40 Years (Southern Poland)

Decline in body size and female fraction in the grass snake (Natrix natrix, Linnaeus 1758) population after 40 years (Southern Poland)

Evolution of parthenogenetic reproduction in Caucasian rock lizards: A review

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