PATTERNS OF HABITAT USE BY PRIMATES IN EASTERN ECUADOR

Lowland tropical rain forests of western Amazonia are characterized by the most speciose primate communities in the Neotropics, immediately leading to the question of to what extent does niche partitioning by primate species serve as a mechanism to promote species co-existence. Because the primate assemblages that we observe today reflect a combination of ecological and evolutionary processes, this study examines habitat occupancy and its relationship to phylogeny and space in a diverse diurnal primate community in an undisturbed lowland rain forest of Amazonian Ecuador. Specifically, the following null hypotheses are explored as potential factors that shape community structure: (1) mean height in the forest strata does not differ among species; (2) species occupy habitat types at frequencies proportional to their overall availability; (3) species do not segregate in ecological space; (4) there is no relationship between phylogenetic distance and ecological distance among species; and (5) there is no relationship between ecological distance and geographic distance among species. The results of this study reveal that ecological differences among the species in this primate community facilitate their coexistence. Larger species generally occupied higher strata than smaller ones. Furthermore, although they generally tended to occupy habitat types at frequencies proportional to their availability in the study area, species segregated in ecological space defined by dissimilarity in habitat occupancy. Finally, in this community, a clear relationship was not observed between phylogenetic and ecological distances or ecological and geographic distances. This study elucidates the spatial distribution and the habitat partitioning of the diurnal primate community at the Tiputini Biodiversity Station in Ecuadorian Amazonia

Determinants of geographic distribution in western North American monkeyflowers

2014 Summer.The geographic range of a species represents the basic unit of biogeography. Despite ample evidence that properties of geographic ranges vary among species, we do not fully understand the ecological and evolutionary processes underlying these patterns, thereby hindering our ability to forecast changes in species' distributions in response to changing environments. Key hypotheses about variation in geographic range size among species emphasize the roles of ecological niche properties and the connectivity of suitable habitat. In the first study of my dissertation, I combined primary occurrence data with climate variables to test the relative importance of these hypotheses in 72 species of western North American monkeyflower (genus Mimulus). Climatic niche breadth, via its effect on the amount of suitable habitat, was a strong predictor of geographic range size, whereas climatic niche position (relative to regional climate) and connectivity of climatically suitable habitat were not. Given the role of climatic niche breadth in shaping geographic range sizes in Mimulus, the goal of the second study of my dissertation was to examine the relationship between thermal tolerance (an important axis of niche breadth) and range size experimentally using 5 pairs of closely related Mimulus species with differing range sizes. Within four species pairs, the more geographically widespread species had a broader thermal tolerance than the narrowly distributed species, providing further support for the hypothesis that species with broader niches are able to achieve larger geographic ranges. Further, within each species pair, the species with broader thermal tolerance encompassed greater variation in temperature across its geographic range and higher genetic variation for thermal tolerance than the species with narrower thermal tolerance, supporting the hypotheses that climatic variability and genetic variation in ecologically important traits can explain variation in environmental tolerance among species. Although species vary in range size, every species has a limited geographic range, leading to the question of what prevents a species from expanding its range via niche evolution. Thus, in the third study of my dissertation, I tested whether adaptation at geographic range margins is constrained by insufficient evolutionary potential. To do so, I used artificial selection experiments to quantify genetic variation in flowering time for populations from the northern edge, center, and southern edge of the geographic range of the scarlet monkeyflower (M. cardinalis). Contrary to prediction, southern populations exhibited significantly greater responses to selection (and thus evolutionary potential) than northern or central populations. Together, these results highlight an important role of niche breadth in explaining variation in geographic range size among species, and reveal variation in evolutionary potential that facilitates niche and range expansion within and among species

The evolution of thermal performance in native and invasive populations of Mimulus guttatus

The rise of globalization has spread organisms beyond their natural range, allowing further opportunity for species to adapt to novel environments and potentially become invaders. Yet, the role of thermal niche evolution in promoting the success of invasive species remains poorly understood. Here, we use thermal performance curves (TPCs) to test hypotheses about thermal adaptation during the invasion process. First, we tested the hypothesis that if species largely conserve their thermal niche in the introduced range, invasive populations may not evolve distinct TPCs relative to native populations, against the alternative hypothesis that thermal niche and therefore TPC evolution has occurred in the invasive range. Second, we tested the hypothesis that clines of TPC parameters are shallower or absent in the invasive range, against the alternative hypothesis that with sufficient time, standing genetic variation, and temperature-mediated selection, invasive populations would re-establish clines found in the native range in response to temperature gradients. To test these hypotheses, we built TPCs for 18 native (United States) and 13 invasive (United Kingdom) populations of the yellow monkeyflower, Mimulus guttatus. We grew clones of multiple genotypes per population at six temperature regimes in growth chambers. We found that invasive populations have not evolved different thermal optima or performance breadths, providing evidence for evolutionary stasis of thermal performance between the native and invasive ranges after over 200 years post introduction. Thermal optimum increased with mean annual temperature in the native range, indicating some adaptive differentiation among native populations that was absent in the invasive range. Further, native and invasive populations did not exhibit adaptive clines in thermal performance breadth with latitude or temperature seasonality. These findings suggest that TPCs remained unaltered post invasion, and that invasion may proceed via broad thermal tolerance and establishment in already climatically suitable areas rather than rapid evolution upon introduction

Data from: Demographic compensation does not rescue populations at a trailing range edge

Species' geographic ranges and climatic niches are likely to be increasingly mismatched due to rapid climate change. If a species' range and niche are out of equilibrium, then population performance should decrease from high-latitude "leading" range edges, where populations are expanding into recently ameliorated habitats, to low-latitude "trailing" range edges, where populations are contracting from newly unsuitable areas. Demographic compensation is a phenomenon whereby declines in some vital rates are offset by increases in others across time or space. In theory, demographic compensation could increase the range of environments over which populations can succeed and forestall range contraction at trailing edges. An outstanding question is whether range limits and range contractions reflect inadequate demographic compensation across environmental gradients, causing population declines at range edges. We collected demographic data from 32 populations of the scarlet monkeyflower (Erythranthe cardinalis) spanning 11˚ latitude in western North America and used integral projection models to evaluate population dynamics and assess demographic compensation across the species' range. During the 5-year study period, which included multiple years of severe drought and warming, population growth rates decreased from north to south, consistent with leading-trailing dynamics. Southern populations at the trailing range edge declined due to reduced survival, growth, and recruitment, despite compensatory increases in reproduction and faster life history characteristics. These results suggest that demographic compensation may only delay population collapse without the return of more favorable conditions or the contribution of other buffering mechanisms such as evolutionary rescue

Data from: The evolution of environmental tolerance and range size: a comparison of geographically restricted and widespread Mimulus

The geographic ranges of closely related species can vary dramatically, yet we do not fully grasp the mechanisms underlying such variation. The niche breadth hypothesis posits that species that have evolved broad environmental tolerances can achieve larger geographic ranges than species with narrow environmental tolerances. In turn, plasticity and genetic variation in ecologically important traits and adaptation to environmentally variable areas can facilitate the evolution of broad environmental tolerance. We used five pairs of western North American monkeyflowers to experimentally test these ideas by quantifying performance across eight temperature regimes. In four species pairs, species with broader thermal tolerances had larger geographic ranges, supporting the niche breadth hypothesis. As predicted, species with broader thermal tolerances also had more within-population genetic variation in thermal reaction norms and experienced greater thermal variation across their geographic ranges than species with narrow thermal tolerances. Species with narrow thermal tolerance may be particularly vulnerable to changing climatic conditions due to lack of plasticity and insufficient genetic variation to respond to novel selection pressures. Conversely, species experiencing high variation in temperature across their ranges may be buffered against extinction due to climatic changes because they have evolved tolerance to a broad range of temperatures

Data from: Artificial selection reveals high genetic variation in phenology at the trailing edge of a species range

Species' responses to climate change depend on the interplay of migration and adaptation, yet we know relatively little about the potential for adaptation. Genetic adaptations to climate change often involve shifts in the timing of phenological events such as flowering. If populations at the edge of a species' range have lower genetic variation in phenological traits than central populations, then their persistence under climate change could be threatened. To test this hypothesis, we performed artificial selection experiments using the scarlet monkeyflower (Mimulus cardinalis) and compared genetic variation in flowering time among populations at the latitudinal center, northern edge, and southern edge of the species' range. We also assessed whether selection on flowering time yielded correlated responses in functional traits, potentially representing a cost associated with early or late flowering. Contrary to prediction, southern populations exhibited greater responses to selection on flowering time than central or northern populations. Further, selection for early flowering resulted in correlated increases in specific leaf area and leaf nitrogen, whereas selection for late flowering led to decreases in these traits. These results provide critical insights about how spatial variation in the potential for adaptation may affect population persistence under changing climates

Mimulus cardinalis data from artificial selection experiment based on a subset of C1 individuals

This data file includes flowering time, measured as number of days from germination to first flower, for each Mimulus cardinalis individual in artificial selection experiment based on a subset of individuals from the C1 population (see publication for further details). Column names are as follows: Generation: year in which artificial selection was performed; parental generation (2012); 1 generation of selection (2013); 2 generations of selection (2014) Line: artificial selection line; early flowering (early); unselected (control); late flowering (late) Family: full-sibling seed family Replicate: replicates of each full-sibling seed family; only relevant in 2013 and 2014 generations Family.Replicate: replicate nested within full-sibling seed family; only relevant in 2013 and 2014 generations FloweringTime: number of days from germination to first flowe

Mimulus cardinalis data from artificial selection experiment

This data file includes flowering time, specific leaf area, leaf nitrogen content, relative growth rate, and carbon isotope ratio for each Mimulus cardinalis individual in experiment (see publication for further details). Column names are as follows: Generation: year in which artificial selection was performed; parental generation (2012); 1 generation of selection (2013); 2 generations of selection (2014) Region: range position from which populations originate; northern edge (N), latitudinal range centre (C), or southern edge (S) Population: location from which individuals were collected (see Fig. 1 and Table 1 in publication) Line: artificial selection line; early flowering (early); unselected (control); late flowering (late) Population.Line: selection line nested within population Par1: identity of parent 1 of each individual in 2013 and 2014 generations; used in calculations of weighted selection differentials Par2: identity of parent 2 of each individual in 2013 and 2014 generations; used in calculations of weighted selection differentials Family: full-sibling seed family Replicate: replicates of each full-sibling seed family; only relevant in 2013 and 2014 generations Family.Replicate: replicate nested within full-sibling seed family; only relevant in 2013 and 2014 generations FloweringTime: number of days from germination to first flower SLA: specific leaf area (mm2/mg); only measured in 2014 generation percent.N: percent leaf nitrogen content; only measured in 2014 generation on a subset of individuals RGR: relative growth rate in early seedling stem length (cm cm-1 day-1); only measured in 2014 generation delta.13C: carbon isotope ratio (δ13C); only measured in 2014 generation on a subset of individual

Annual climate data for each study population from 1951-2014

Annual climate data for each Erythranthe (Mimulus) cardinalis study population from 1951-2014. Data were obtained from ClimateWNA version 5.41 (Wang T, Hamann A, Spittlehouse DL, Murdock TQ; 2012; "ClimateWNA - High-resolution spatial climate data for western North America," J Appl Meteorol Climatol 51:16-29). ID1: Population, MAT: Mean annual temperature, MAP: Mean annual precipitation