Grasshopper Community Response to Climatic Change: Variation Along an Elevational Gradient

Abstract

BackgroundThe impacts of climate change on phenological responses of species and communities are well-documented; however, many such studies are correlational and so less effective at assessing the causal links between changes in climate and changes in phenology. Using grasshopper communities found along an elevational gradient, we present an ideal system along the Front Range of Colorado USA that provides a mechanistic link between climate and phenology.Methodology/Principal FindingsThis study utilizes past (1959–1960) and present (2006–2008) surveys of grasshopper communities and daily temperature records to quantify the relationship between amount and timing of warming across years and elevations, and grasshopper timing to adulthood. Grasshopper communities were surveyed at four sites, Chautauqua Mesa (1752 m), A1 (2195 m), B1 (2591 m), and C1 (3048 m), located in prairie, lower montane, upper montane, and subalpine life zones, respectively. Changes to earlier first appearance of adults depended on the degree to which a site warmed. The lowest site showed little warming and little phenological advancement. The next highest site (A1) warmed a small, but significant, amount and grasshopper species there showed inconsistent phenological advancements. The two highest sites warmed the most, and at these sites grasshoppers showed significant phenological advancements. At these sites, late-developing species showed the greatest advancements, a pattern that correlated with an increase in rate of late-season warming. The number of growing degree days (GDDs) associated with the time to adulthood for a species was unchanged across the past and present surveys, suggesting that phenological advancement depended on when a set number of GDDs is reached during a season.ConclusionsOur analyses provide clear evidence that variation in amount and timing of warming over the growing season explains the vast majority of phenological variation in this system. Our results move past simple correlation and provide a stronger process-oriented and predictive framework for understanding community level phenological responses to climate change.

Species' traits predict phenological responses to climate change in butterflies

“…This may reflect the fact that species that emerge earlier have experienced a greater mean increase in spring temperature (1.58C) relative to summer (1.08C) since 1975 or tend to overwinter in more advanced stages (Dennis 1993). The timing of warming has been observed to influence the phenological responses of early-and lateseason grasshoppers (Nufio et al 2010).…”

Elevational differences in developmental plasticity determine phenological responses of grasshoppers to recent climate warming

“…Weekly survey data from 1959 to 1960 were assembled from field notebooks as part of the Gordon Alexander Project (ghopclimate.colorado.edu). Weekly resurveys have been conducted since 2006 [11] following the original protocol, consisting of 1.5 person-hours of sweep netting (divided among one to three surveyors) and 0.75 personhours of searching for adults and juveniles that may have been missed by sweep netting [12]. We focus on four univoltine (annual) grasshopper species that are abundant across the elevation gradient and study period: Camnula pellucida, Melanoplus boulderensis, Melanoplus dawsoni and Melanoplus sanguinipes.…”

“…We focus on four univoltine (annual) grasshopper species that are abundant across the elevation gradient and study period: Camnula pellucida, Melanoplus boulderensis, Melanoplus dawsoni and Melanoplus sanguinipes. Each species overwinters in an egg diapause, but they differ in their seasonal timing and dispersal ability: in particular, C. pellucida and M. boulderensis are 'early' species that complete post-diapause development earlier in the season, whereas M. dawsoni and M. sanguinipes are 'late' species [11]. Melanoplus dawsoni and M. boulderensis have short wings and thus a limited capacity for dispersal.…”

“…This is also in response to our only having an LDT estimate from rearing for M. sanguinipes. We used a LDT of 12.08C [11] to account for differences between air and body temperatures. We additionally estimated degree days as above for M. sanguinipes to confirm that the results were robust to the degree days calculation methods.…”

Who flies first? – habitat‐specific phenological shifts of butterflies and orthopterans in the light of climate change: a case study from the south‐eastMediterranean

“…There is ample evidence that climate warming is linked to a changing onset of phenological events for a variety of taxonomic groups (Menzel et al, 2006;Parmesan, 2007;Primack et al, 2009), including acceleration of spring leaf unfolding and first flowering of wild plants (Badeck et al, 2004;Menzel et al, 2006), changed arrival dates of migrant bird species (Huin & Sparks, 2000;Robson & Barriocanal, 2011), and the advanced appearance of butterflies, orthopterans, and other insects (Roy & Sparks, 2000;Walther et al, 2002;Forister & Shapiro, 2003;Stefanescu et al, 2003;Nufio et al, 2010). The phenology of insects can be particularly sensitive even to minor changes in temperature, considering that their life-history traits (e.g.…”