Additive effects of temperature and water availability on pregnancy in a viviparous lizard

Abstract

One of the greatest current threats to biodiversity is climate change. However, understanding of organismal responses to fluctuations in temperature and water availability is currently lacking, especially during fundamental life-history stages such as reproduction. To further explore how temperature and water availability impact maternal physiology and reproductive output, we used the viviparous form of the European common lizard (Zootoca vivipara) in a two-by-two factorial design manipulating both hydric and thermal conditions, for the first time. We collected blood samples and morphological measurements during early pregnancy and post-parturition to investigate how water availability, temperature and a combination of the two influence maternal phenology, morphology, physiology and reproductive output. We observed that dehydration during gestation negatively affects maternal physiological condition (lower mass gain, higher tail reserve mobilization) but has little effect on reproductive output. These effects are mainly additive to temperature regimes, with a proportional increase in maternal costs in warmer environments. Our study demonstrates the importance of considering combined effects of water and temperature when investigating organismal responses to climate changes, especially during periods crucial for species survival such as reproduction.

Reproducing in a changing world: combined effects of thermal conditions by day and night and of water constraints during pregnancy in a cold‐adapted ectotherm

“…Second, all females experienced muscle loss during the experiment and losses were highest in females in dry conditions, especially if they had limited access to preferred temperatures during the daytime. Muscle wasting during pregnancy is common in reptiles (Lourdais et al 2004, 2013, Lorioux et al 2016) and skeletal muscle has been shown to be an important substrate for the reallocation of hydric resources when demands are high and intake is limited (Brusch et al 2019, 2020, Dezetter et al 2021). Because proteins are a much lower energetic source compared to lipids and their oxidation provides five times more water (Jenni and Jenni‐Eiermann 1998), increased muscle catabolism likely supported the hydric costs of reproduction in our study.…”

“…As intermediates on the capital-income breeding spectrum, Z. vivipara can accumulate vast lipid reserves after parturition, prior to hibernation (Avery 1975), but are also able to assimilate nutrients during pregnancy (Bleu et al 2013). Previous studies have found that higher temperatures, compounded by dehydration, reduce tail reserves in gestating lizards (Brusch et al 2020). Our results align with this and further suggest a potential tradeoff between tail reserves and fecundity, where larger female with small litter size are able to assimilate and invest nutrients into tail reserves but only if water is readily available (Fig.…”

“…Reproductive mode may drive vulnerability to climate changes and viviparous species may be more susceptible because of substantial maternal investment during pregnancy (Pincheira‐Donoso et al 2013). In addition, viviparity generates parent–offspring conflicts for energetic resources (Calow 1973, Doughty and Shine 1997, Reznick et al 2000, Kotiaho 2001) and hydric resources (Dupoue et al 2015, Brusch et al 2017, 2019, 2020, Dupoué et al 2018, Brusch and DeNardo 2019), which may be altered by climate change.…”

“…Second, conversely, warmer nights would have a net negative impact on reproduction by increasing metabolic demands without providing thermal benefits for foraging (Rutschmann et al 2021). Third, water constraints would overall negate potential thermal benefits by negatively impacting maternal physiology (Brusch et al 2020).…”

Few studies of wild animal performance account for parasite infections: A systematic review

“…Furthermore, researchers may also specify when ectoparasites are forcibly removed and animals have been exposed to an anti‐parasite treatment or spray prior to experiments. For example, Brusch et al (2020) used an anti‐parasite spray (Frontline, Merial Inc.) on European lizards Zootoca vivipara and removed visible parasites using forceps. A treatment upon arrival in the laboratory is another efficient option.…”