Mosquito traits
As selection acts on specific phenotypes, ‘adaptation’ here refers to a
change in the thermal tolerance of a specific mosquito trait—an
emergent property that reflects underlying changes in the thermal
sensitivity of proteins (Somero 1995, 2003, 2010). The critical traits
to examine are those with the strongest climate sensitivity and the
strongest impact on overall mosquito fitness. We hypothesize that
warming temperatures will impose the strongest selection pressure on
traits with the lowest thermal optima and critical thermal maxima. For
many mosquito species, these traits are adult lifespan and immature
survival (reviewed in Mordecai et al. 2019). However, whether these
traits also pose the strongest constraints on mosquito fitness and
persistence at high temperatures remains poorly understood because prior
work has largely focused on mosquito traits related to disease
transmission during the activity season, but there may be additional
traits that help mosquitoes tolerate thermal extremes. For this reason,
we consider several fitness-relevant mosquito life history traits (e.g.,
survival, development rates, and fecundity). Additionally, we consider
various metrics that describe trait thermal tolerance (e.g., time to
partial paralysis, known as ‘knockdown time’ at high temperatures, trait
performances at high temperatures, and temperatures causing 50% sample
mortality) because they may provide differing information on species
adaptive potential (Hangartner and Hoffmann 2016). The framework
outlined here can be applied to any specific trait and measurement.