Extinction debt and delayed colonization have had comparable but unique effects on plant community–climate lags since the Last Glacial Maximum

Abstract

Aim Plant communities typically exhibit lagged responses to climate change due to poorly understood effects of colonization and local extinction. Here, we quantify rates of change in mean cold tolerances, and contributions of colonization and local extinction to those rates, recorded in plant macrofossil assemblages from North American hot deserts over the last 30,000 years. Location Mojave, Sonoran and Chihuahuan Deserts. Time period 30–0 thousand years before present (kybp). Major taxa studied Vascular plants. Methods Colonization and local extinction dates for 269 plant species were approximated from macrofossils in 15 packrat (Neotoma) midden series. Cold tolerances estimated from contemporary climate were used to quantify assemblage‐mean cold tolerances through time. Rates of colonization and local extinction, and their effects on rates of change in assemblage‐mean cold tolerances, were estimated for 30–20 kybp (Late Pleistocene, no directional warming), 20–10 kybp (deglaciation, rapid warming) and 10–0 kybp (Holocene, no directional warming). Results Rates of change in all metrics were negligible during the Late Pleistocene. Rates of change in assemblage‐mean cold tolerances (mean 1.0°C × 10−4/yr) lagged behind warming during deglaciation, and continued at similar rates (1.2°C × 10−4/yr) throughout the Holocene. Colonization and local extinction contributed equally to delayed responses to warming, but their dynamics differed through time: Colonization by warm‐adapted species predominated during deglaciation, while the most heat‐adapted species exhibited long delays in colonization. Only the most cold‐adapted species went locally extinct during deglaciation, followed by slow repayment of the extinction debt of cool‐adapted species during the Holocene. Main conclusions Responses to rapid warming can persist for millennia, even after cessation of warming. Consistent patterns from different midden series across the region support a metacommunity model in which dispersal interacts with environmental filters and buffers against local extinction to drive community–climate disequilibrium during and after periods of warming.

Life history traits predict colonization and extinction lags of desert plant species since the Last Glacial Maximum

“…1b). Focal communities lagged behind warming during deglaciation and continued to respond to past warming throughout much of the Holocene (Butterfield et al 2019), thus leading to the assumption that differences in the timing of colonization and extinction among species should be proportional to their differences in temperature tolerances. The same was calculated for local extinction dates by replacing z col with z ext in the preceding equation.…”

“…Temperature increased during deglaciation, although not consistently, and then became fairly stable during the Holocene. Focal communities lagged behind warming during deglaciation and continued to respond to past warming throughout much of the Holocene (Butterfield et al 2019), thus leading to the assumption that differences in the timing of colonization and extinction among species should be proportional to their differences in temperature tolerances. This approach of comparing relative climatic tolerances was used due to the potential for climatic tolerances to have evolved through time, as well as a lack of downscaled high temporal and spatial resolution climatic reconstructions.…”

“…In a previous study with this data set, we used estimates of species' contemporary cold tolerances to demonstrate that assemblage-mean cold tolerance lagged substantially behind climate warming during deglaciation, resulting in continued species turnover throughout the Holocene as communities slowly caught up with past warming (Butterfield et al 2019). middens to assess the effects of plant traits on variation in colonization and extinction lags since the Last Glacial Maximum (LGM;~21.5 thousand years ago) across the hot deserts-Mojave, Sonoran, and Chihuahuan-of North America.…”

“…middens to assess the effects of plant traits on variation in colonization and extinction lags since the Last Glacial Maximum (LGM;~21.5 thousand years ago) across the hot deserts-Mojave, Sonoran, and Chihuahuan-of North America. In a previous study with this data set, we used estimates of species' contemporary cold tolerances to demonstrate that assemblage-mean cold tolerance lagged substantially behind climate warming during deglaciation, resulting in continued species turnover throughout the Holocene as communities slowly caught up with past warming (Butterfield et al 2019). Inconsistencies in this trend were still evident, and we hypothesized that interspecific variation in traits related to dispersal and demographic persistence could play a role in determining why some species colonize or go extinct, respectively, later than expected.…”

Paleo‐metagenomics of North American fossil packrat middens: Past biodiversity revealed by ancient DNA

“…Since 1994, another 1,000 middens produced by other rodents ( Abrocoma , Phyllotis ) have been studied from western South America (Latorre, Betancourt, Rylander, & Quade, ). Middens provide rich sources of fossil material from both plants and animals, which can be used to investigate ecological responses to environmental change over the last 50,000 years (Balk, Betancourt, & Smith, ; Becklin, Medeiros, Sale, & Ward, ; Butterfield, Anderson, Holmgren, & Betancourt, ; Butterfield, Holmgren, Anderson, & Batancourt, ; Dézerald, Latorre, Betancourt, Brito Vera, & González, ; Holmgren, Hunter, & Betancourt, ).…”