Size-related mortality during overwintering in cavity-nesting ant colonies (Hymenoptera: Formicidae)

Mitrus, Sławomir

doi:10.14411/eje.2016.070

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…The absence of a positive effect of colony size on worker survival is somewhat surprising given that it was linked to colony growth and reproductive success in this species [ 54 ]. The lack of a relationship between the colony size and colony survival during winter is also found in other studies on Temnothorax [ 14 , 30 , 64 ]. The high survival rate of both queens and workers in our study during winter is unexpected.…”

Section: Discussionsupporting

confidence: 75%

Worker Size Diversity Has No Effect on Overwintering Success under Natural Conditions in the Ant Temnothorax nylanderi

Honorio

Doums

Molet

2021

Insects

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Winter is a difficult period for animals that live in temperate zones. It can inflict high mortality or induce weight loss with potential consequences on performance during the growing season. Social groups include individuals of various ages and sizes. This diversity may improve the ability of groups to buffer winter disturbances such as starvation or cold temperature. Studies focusing on the buffering role of social traits such as mean size and diversity of group members under winter conditions are mainly performed in the laboratory and investigate the effect of starvation or cold separately. Here, we experimentally decreased worker size diversity and manipulated worker mean size within colonies in order to study the effect on overwintering survival in the ant Temnothorax nylanderi. Colonies were placed under natural conditions during winter. Colony survival was high during winter and similar in all treatments with no effect of worker size diversity and mean worker size. Higher brood survival was positively correlated with colony size (i.e., the number of workers). Our results show that the higher resistance of larger individuals against cold or starvation stresses observed in the laboratory does not directly translate into higher colony survival in the field. We discuss our results in the light of mechanisms that could explain the possible non-adaptive size diversity in social species.

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Section: Discussionsupporting

confidence: 75%

Worker Size Diversity Has No Effect on Overwintering Success under Natural Conditions in the Ant Temnothorax nylanderi

Honorio

Doums

Molet

2021

Insects

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“…Variance in temperature in the urban habitat along with microclimatic differences between urban and rural sites, such as differences in snow cover (Groffman et al, 2001), could paradoxically lead to colder soil temperature extremes in urban areas, even if average air temperatures remain higher. This difference is likely due to smaller or more infrequent snowpack at urban habitats which can reduce soil level insulation and increase microsite temperature variability with consequences for urban populations (Mitrus, 2016;Thompson et al, 2016;Williams et al, 2015). Urban soil temperature profiles at the height that acorn ants would experience them are characterized by frequent cold-term shocks, but warmer overall temperatures (Thompson et al, 2016), potentially providing an advantage to colonies that had retained a rapid CCRT like their rural counterparts.…”

Section: Discussionmentioning

confidence: 99%

Keep your cool: Overwintering physiology in response to urbanization in the acorn ant, Temnothorax curvispinosus

Prileson¹,

Clark²,

Diamond³

et al. 2023

Preprint

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Winter presents an immense challenge for survival, yet temperate ectotherms have remarkable adaptations to physiologically compensate for these challenges. Such mechanisms are especially relevant under recent climate change where responses to warmer winters might negatively affect populations. While there is growing evidence of thermal physiological adaptations and population divergence in response to contemporary warming from the growing season, the impact of warming on overwintering ectotherms is less clear. To address this knowledge gap, we use a common garden experiment with urban and rural populations of the acorn ant, Temnothorax curvispinosus, to explore divergence in thermal physiological traits assessed following winter acclimation. Specifically, we use the thermal gradient of the urban heat island to assess population divergence in cold tolerance (chill coma recovery), metabolic rate, thermal sensitivity of metabolic rate, heat tolerance and colony demographics. Our results show there was no evidence of evolutionary divergence in low-temperature performance (chill coma recovery, metabolic rate at either of two test temperatures (4 and 10 °C) or acute thermal sensitivity of metabolic rate) among urban and rural colonies which differs from previous tests of warm-season acclimated ants. In contrast, we found winter-acclimated urban ants exhibited higher heat tolerance than rural ants with a magnitude of difference similar to growing season tests. These findings indicate that acclimation under overwintering conditions might dampen the expression of urban-rural population divergence in some thermal physiological traits and broadly suggest the potential importance of retaining at least some components of low-temperature physiology when evolving to urban heat islands and contemporary warming.

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“…In the temperate ant species shifting to the bottom nest region before overwintering might enable to avoid low temperatures which are known to be a mortality factor for ants (Berman et al ., 2010; Mitrus, 2016). Thus, the observed pattern of worker distribution in F. fusca colonies raises the question about the possible adaptive significance of distributing some of the workers at depths with higher mortality risk.…”

Section: Discussionmentioning

confidence: 99%

Functional spatial distribution and sociometric characteristics of Formica fusca ants during winter dormancy

Włodarczyk

2020

Ecological Entomology

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1. Ant colonies passing through the period of winter dormancy are subject to the two conflicting selective pressures: (i) on escaping the coldest temperatures during the winter by hiding deep into the soil and (ii) on the reactivation after overwintering as soon as the weather conditions become favourable and the soil surface is warm enough. 2. If selective pressures associated with overwintering are affected differently by the spatial variation in the climate conditions then different overwintering strategies can be expected to occur across geographical gradients. 3. In this study, Formica fusca colonies were excavated in northeastern Poland to examine the spatial distribution of overwintering ants. It has been found that queens, accompanied by part of the workers, shelter themselves at a depth close to the colony's lower limit. However, workers were clustered at different depths along the soil profile, including a few centimetres from the soil surface. 4. Natural selection might promote to allocate individuals who are less valuable to the colony to more risky tasks (e.g. those performed outside the nest). Thus, playing the role of a forager should be associated with the occupation of more risky positions during overwintering. However, no statistically significant difference has been found between workers overwintering in the upper and lower soil strata in their propensity to explore the experimental arena. 5. The observed pattern of the spatial distribution of overwintering ants indicates the existence of a trade-off between winter mortality, costs of physiological adaptations, and the time needed for a colony to reactivate in response to temperature increase.

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Size-related mortality during overwintering in cavity-nesting ant colonies (Hymenoptera: Formicidae)

Cited by 6 publications

References 18 publications

Worker Size Diversity Has No Effect on Overwintering Success under Natural Conditions in the Ant Temnothorax nylanderi

Worker Size Diversity Has No Effect on Overwintering Success under Natural Conditions in the Ant Temnothorax nylanderi

Keep your cool: Overwintering physiology in response to urbanization in the acorn ant, Temnothorax curvispinosus

Functional spatial distribution and sociometric characteristics of Formica fusca ants during winter dormancy

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