Insects in temperate urban parks face stronger selection pressure from the cold than the heat

Bujan, Jelena; Bertelsmeier, Cleo; Ješovnik, Ana (2024) Insects in temperate urban parks face stronger selection pressure from the cold than the heat. Ecology and Evolution, 14 (8). ISSN 2045-7758

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Abstract

Urban areas experience higher temperatures compared to rural areas and as such, areincreasingly considered places of acclimatization and adaptation to warming. Smallectotherms, such as insects, whose body temperature rises with habitat temperature,are directly affected by temperature changes. Thus, warming could have a profoundeffect on insect behavior and physiology. To test if the urban heat island effect driveshigher thermal tolerance and activity changes, we used globally distributed and abun-dant insects—ants. We measured the heat and cold tolerance of 14 ant species distrib-uted across urban and peri-urban areas. As thermal traits are often correlated with antforaging, we measured foraging activity during three consecutive years across eightsites. Contrary to our prediction, ants exposed to the urban heat island effect didnot have a higher heat tolerance than peri-urban ants. Instead, cold tolerance variedacross habitats, with ants from the cooler, peri-urban habitats being able to toleratelower temperatures. We recorded the same pattern of invariant heat and higher coldtolerance for ants in the canopy, compared to ground nesting ants. Ant activity wasalmost 10 times higher in urban sites and best predicted by cold, not heat tolerance.These unexpected results suggest that we need to rethink predictions about urbanheat islands increasing insect heat tolerance in urban habitats, as cold tolerance mightbe a more plastic or adaptable trait, particularly in the temperate zone.

Item Type:	Article
Uncontrolled Keywords:	ants; CTmax; CTmin; ecophysiology; insects; microclimates; peri-urban; thermal tolerance; urban green spaces
Subjects:	NATURAL SCIENCES > Biology > Ecology
Divisions:	Division for Marine and Enviromental Research
Depositing User:	Lorena Palameta
Date Deposited:	29 Aug 2024 11:22
URI:	http://fulir.irb.hr/id/eprint/9033
DOI:	10.1002/ece3.11335

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