Authors: Fhallon Ware-Gilmore, Mario Novelo, Carla M Sgrò, Matthew D Hall, and Elizabeth A McGraw

Published in: Philosophical Transactions of the Royal Society B

Abstract

The geographical range of the mosquito vector for many human disease-causing viruses, Aedes aegypti, is expanding, in part owing to changing climate. The capacity of this species to adapt to thermal stress will affect its future distributions.

It is unclear how much heritable genetic variation may affect the upper thermal limits of mosquito populations over the long term. Nor are the genetic pathways that confer thermal tolerance fully understood.

In the short term, cells induce a plastic, protective response known as ‘heat shock’.

Using a physiological ‘knockdown’ assay, we investigated mosquito thermal tolerance to characterize the genetic architecture of the trait.

To test variation in mosquito thermal sensitivity, we submerged glass vials containing mosquitoes in a tank of water heated to 42°C, representing the upper critical thermal limit for the mosquitoes as determined by pilot assay. We then monitored the time it took for mosquitoes to become immobilized, or the ‘knockdown’ time, using a barcode scanner. For the other half of this design, we heat-shocked mosquitoes from the same families as the aforementioned mosquitoes measured for knockdown for 15 minutes at 42°C to induce stress-based expression. We then examined the expression of key heat shock genes (Hsps) in selected families.

While families representing the extreme ends of the distribution for knockdown time differed from one another, the trait exhibited low but non-zero broad-sense heritability.

We then explored whether families representing thermal performance extremes differed in their heat shock response by measuring gene expression of heat shock protein-encoding genes Hsp26, Hsp83 and Hsp70.

Contrary to prediction, the families with higher thermal tolerance demonstrated less Hsp expression.

This pattern may indicate that other mechanisms of heat tolerance, rather than heat shock, may underpin the stress response, and the costly production of HSPs may instead signal poor adaptation.

Citation

Ware-Gilmore F, Novelo M, Sgrò CM, Hall MD, McGraw EA (2023) Assessing the role of family level variation and heat shock gene expression in the thermal stress response of the mosquito Aedes aegypti. Philosophical Transactions of the Royal Society B PDF DOI

Authors: Laura M Thompson, Lindsey L Thurman, Carly N Cook, Erik A Beever, Carla M Sgrò, Andrew Battles, Carlos A Botero, John E Gross, Kimberly R Hall, Andrew P Hendry, Ary A Hoffmann, Christopher Hoving, Olivia E LeDee, Claudia Mengelt, Adrienne B Nicotra, Robyn A Niver, Felipe Pérez‐Jvostov, Rebecca M Quiñones, Gregor W Schuurman, Michael K Schwartz, Jennifer Szymanski, and Andrew Whiteley

Published in: Conservation Science and Practice

Abstract

Resource managers have rarely accounted for evolutionary dynamics in the design or implementation of climate change adaptation strategies.

We brought the research and management communities together to identify challenges and opportunities for applying evidence from evolutionary science to support on-the-ground actions intended to enhance species’ evolutionary potential. We amalgamated input from natural-resource practitioners and interdisciplinary scientists to identify information needs, current knowledge that can fill those needs, and future avenues for research.

Three focal areas that can guide engagement include:

1. recognizing when to act,
2. understanding the feasibility of assessing evolutionary potential, and
3. identifying best management practices.

Although researchers commonly propose using molecular methods to estimate genetic diversity and gene flow as key indicators of evolutionary potential, we offer guidance on several additional attributes (and their proxies) that may also guide decision-making, particularly in the absence of genetic data.

Finally, we outline existing decision-making frameworks that can help managers compare alternative strategies for supporting evolutionary potential, with the goal of increasing the effective use of evolutionary information, particularly for species of conservation concern. We caution, however, that arguing over nuance can generate confusion; instead, dedicating increased focus on a decision-relevant evidence base may better lend itself to climate adaptation actions.

Historically, the rusty-patched bumble bee (Bombus affinis) was broadly distributed across prairies and grass-land habitats in eastern and upper-midwest Canada and the USA. The species experienced a widespread and steep decline in the early 2000s, precipitating its endangered status. Today, the species is extant in 11 US states and 1 Canadian province, a >50% reduction in its native range. The exact cause of the decline is unknown, but evidence suggests a synergistic interaction between an introduced pathogen and exposure to pesticides.Image credit: USFWS Midwest Region from United States, via Wikimedia Commons

Citation

Thompson LM, Thurman LL, Cook CN, Beever EA, Sgrò CM, Battles A, Botero CA, Gross JE, Hall KR, Hendry AP, Hoffmann AA, Hoving C, LeDee OE, Mengelt C, Nicotra AB, Niver RA, Pérez‐Jvostov F, Quiñones RM, Schuurman GW, Schwartz MK, Szymanski J, Whiteley A (2023) Connecting research and practice to enhance the evolutionary potential of species under climate change. Conservation Science and Practice PDF DOI

Authors: Brooke Zanco, Lisa Rapley, Joshua N Johnstone, Amy Dedman, Christen K Mirth, Carla M Sgrò, and Matthew DW Piper

Published in: Journal of Insect Physiology

Abstract

Limiting calories or specific nutrients without malnutrition, otherwise known as dietary restriction (DR), has been shown to extend lifespan and reduce reproduction across a broad range of taxa.

Our recent findings in Drosophila melanogaster show that supplementing flies on macronutrient-rich diets with additional cholesterol can extend lifespan to the same extent as DR, while also sustaining high egg production. Thus, DR may be beneficial for lifespan because it reduces egg production which in turn reduces the mother’s demand for sterols, thus supporting longer lifespan. It is also possible that mothers live longer and lay more eggs on high sterol diets because the diet triggers enhanced somatic maintenance and promotes egg production, but at the cost of diminished egg quality.

To test this, we measured the viability of eggs and development of offspring from mothers fed either cholesterol-sufficient or cholesterol-limiting diets.

We found that even when the mother’s diet was completely devoid of cholesterol, viable egg production persisted for ∼10 days. Furthermore, we show that sterol-supplemented flies with long lives lay eggs that have high viability and the same developmental potential as those laid by shorter lived mothers on sterol limiting diets.

These findings suggest that offspring viability is not a hidden cost of lifespan extension seen in response to dietary sterol supplementation.

Sterol-supplemented flies with long lives lay eggs that have high viability and the same developmental potential as those laid by shorter lived mothers on sterol limiting diets.

Citation

Zanco B, Rapley L, Johnstone JN, Dedman A, Mirth CK, Sgrò CM, Piper MDW (2023) Drosophila melanogaster females prioritise dietary sterols for producing viable eggs. Journal of Insect Physiology PDF DOI