Determinants of local abundance in a major radiation of Australian passerines (Aves: Meliphagoidea)

Aim  To identify the factors that contribute to variation in abundance (population density), and to investigate whether habitat breadth and diet breadth predict macroecological patterns in a suborder of passerine birds (Meliphagoidea).
Location  Australia (including Tasmania).
Methods  Mean abundance data were collated from site surveys of bird abundance (the Australian Bird Count); range size and latitudinal position data from published distribution maps; and body mass and diet breadth information from published accounts. A diversity index of habitats used (habitat breadth) was calculated from the bird census data. We used bivariate correlation and multiple regression techniques, employing two phylogenetic comparative methods: phylogenetic generalized least squares and independent contrasts.
Results  Body mass and latitude were the only strong predictors of abundance, with larger-bodied and lower-latitude species existing at lower densities. Together, however, body mass and latitude explained only 11.1% of the variation in mean abundance. Range size and habitat breadth were positively correlated, as were diet breadth and body mass. However, neither range size, nor habitat breadth and diet breadth, explained patterns in abundance either directly or indirectly.
Main conclusions  Levels of abundance (population density) in meliphagoid birds are most closely linked to body mass and latitudinal position, but not range size. As with many other macroecological analyses, we find little evidence for aspects of niche breadth having an effect on patterns of abundance. We hypothesize that evolutionary age may also have a determining effect on why species tend to be rarer (less abundant) in the tropics.     

The relationship between geographic range size and life history traits: is biogeographic history uncovered? A test using the Iberian butterflies

The geographic range of a species is influenced by past phylogenetic and biogeographic patterns. However, other historical interactions, including the interplay between life history and geography, are also likely involved. Therefore, the range size of a species can be explained on the basis of niche‐breadth or dispersal related hypotheses, and previous work on European butterflies suggests that both, under the respective guise of ecological specialisation and colonising ability may apply. In the present study, data from 205 species of butterflies from the Iberian peninsula were processed through multiple regression analyses to test for correlations between geographic range size, life history traits and geographic features of the species distribution types. In addition, the percentage of variance explained by the subsets of variables analyzed in the study, with and without control for phylogenetic effects was tested. Despite a complex pattern of bivariate correlations, we found that larval polyphagy was the single best correlate of range size, followed by dispersal. Models that combined both life history traits and geographic characteristics performed better than models generated independently. The combined variables explained at least 39% of the variance. Bivariate correlations between range size and body size, migratory habits or egg size primarily reflected taxonomic patterning and reciprocal correlations with larval diet breadth and adult phenology. Therefore, aspects of niche breadth i.e. potential larval diet breadth emerged as the most influential determinants of range size. However, the relationships between these types of ecological traits and biogeographic history must still be considered when associations between life history and range size are of interest.     

Antagonistic selection between adult thorax and wing size in field released Drosophila melanogaster independent of thermal conditions

Attempts to explain size variation in Drosophila and other small insects often focus on the larval stage and association between development time and size, but patterns are also influenced by direct selection on size-related traits in the adults. Here we use multiple field releases of Drosophila melanogaster to test the association between size and one component of field fitness, the ability of Drosophila to locate resources for feeding and breeding. We find antagonistic selection between wing length and thorax length in both males and females, such that capture at baits is higher for flies with relatively larger thorax lengths and smaller wings. However flies with large wings relative to thoraces disperse further as reflected in the longer distances moved to baits. These patterns did not depend strongly on weather conditions, suggesting that selection on adult size is at least partly independent of temperature. Antagonistic selection between size traits can generate changes in size along gradients if the distribution of resources in the environment varies and selects for different dispersal patterns, particularly as dispersal is relatively higher under warmer conditions.     

Higher investment in flight morphology does not trade off with fecundity estimates in a poleward range‐expanding damselfly

1. Evolutionary increases in dispersal‐related traits are frequently documented during range expansions. Investment in flight‐related traits is energetically costly and a trade‐off with fecundity may be expected during range expansion. 2. However, in contrast to wing‐dimorphic species, this trade‐off is not general in wing‐monomorphic species. In the absence of a dispersal‐‐fecundity trade‐off, an increased investment in clutch size at the expansion front is expected possibly at a cost of reduced offspring size. 3. The study evaluated investment in female flight morphology and fecundity‐related traits (clutch size, hatchling size) and potential trade‐offs among these traits in replicated populations of the poleward range‐expanding damselfly Coenagrion scitulum. 4. Females at the expansion front had a higher relative thorax length, indicating an increased investment in flight; this can be explained by spatial sorting of dispersal ability or in situ natural selection at the expansion front. Edge females produced larger hatchlings, however, this pattern was totally driven by the population‐specific thermal larval regimes and could not be attributed to the range expansion per se. By contrast, clutch sizes did not differ between core and edge populations. There was no signal of a dispersal–fecundity trade‐off either for a trade‐off between clutch size and hatchling size. 5. These results indicate that evolution of a higher dispersal ability at the expansion front of C. scitulum does not trade off with investment in fecundity, hence a dispersal–fecundity trade‐off is unlikely to slow down range expansion of this species.     

Species’ traits as predictors of range shifts under contemporary climate change: A review and meta‐analysis

A growing body of literature seeks to explain variation in range shifts using species’ ecological and life‐history traits, with expectations that shifts should be greater in species with greater dispersal ability, reproductive potential, and ecological generalization. Despite strong theoretical support for species’ traits as predictors of range shifts, empirical evidence from contemporary range shift studies remains limited in extent and consensus. We conducted the first comprehensive review of species’ traits as predictors of range shifts, collecting results from 51 studies across multiple taxa encompassing over 11,000 species’ responses for 54 assemblages of taxonomically related species occurring together in space. We used studies of assemblages that directly compared geographic distributions sampled in the 20th century prior to climate change with resurveys of distributions after contemporary climate change and then tested whether species traits accounted for heterogeneity in range shifts. We performed a formal meta‐analysis on study‐level effects of body size, fecundity, diet breadth, habitat breadth, and historic range limit as predictors of range shifts for a subset of 21 studies of 26 assemblages with sufficient data. Range shifts were consistent with predictions based on habitat breadth and historic range limit. However, body size, fecundity, and diet breadth showed no significant effect on range shifts across studies, and multiple studies reported significant relationships that contradicted predictions. Current understanding of species’ traits as predictors of range shifts is limited, and standardized study is needed for traits to be valid indicators of vulnerability in assessments of climate change impacts.     

Wing morphology and migration status,but not body size,habitat or Rapoport's rule predict range size in North‐American dragonflies (Odonata: Libellulidae)

Understanding why species range sizes vary is important for predicting the impact of environmental change on biodiversity. Here we use a multi‐variable approach in a phylogenetic comparative context to understand how four morphological, two ecological, and two eco‐geographical variables are associated with range size, latitudinal range and longitudinal range in 81 species of North‐American libellulid dragonflies. Our results show that: 1) migratory species and species with a more expanded basal hindwing lobe have a larger range size; 2) opposite to Rapoport's rule, latitudinal range is negatively correlated with mid‐range latitude; 3) longitudinal range is predicted by wing morphology and migration; 4) body size and larval habitat are not correlated with range size, latitudinal range or longitudinal range. These results suggest that dispersal‐related traits, such as wing shape and migratory status, are important factors in predicting the range size of libellulid dragonflies. In addition, the reverse Rapoport's rule suggests that more northern‐centred species might be more specialized than more southern‐centred species. We suggest that the variables predicting range size are likely imposed by taxon‐specific morphological, ecological, physiological and behavioural traits. Taxon‐specific knowledge is thus necessary to understand the dynamics of range sizes and is important to implement successful restoration and conservation plans of threatened species.     

Niche breadth explains the range size of European-centred butterflies,but dispersal ability does not

Aim

The breadth of ecological niches and dispersal abilities have long been discussed as important determinants of species' range sizes. However, studies directly comparing the relative effects of both factors are rare, taxonomically biased and revealed inconsistent results.

Location

Europe.

Time Period

Cenozoic.

Major Taxa

Butterflies, Lepidoptera.

Methods

We relate climate, diet and habitat niche breadth and two indicators of dispersal ability, wingspan and a dispersal tendency index, to the global range size of 369 European-centred butterfly species. The relative effects of these five predictors and their variation across the butterfly phylogeny were assessed by means of phylogenetic generalized least squares models and phylogenetically weighted regressions respectively.

Results

Climate niche breadth was the most important single predictor, followed by habitat and diet niche breadth, while dispersal tendency and wingspan showed no relation to species' range size. All predictors together explained 59% of the variation in butterfly range size. However, the effects of each predictor varied considerably across families and genera.

Main Conclusions

Range sizes of European-centred butterflies are strongly correlated with ecological niche breadth but apparently independent of dispersal ability. The magnitude of range size–niche breadth relationships is not stationary across the phylogeny and is often negatively correlated across the different dimensions of the ecological niche. This variation limits the generalizability of range size–trait relationships across broad taxonomic groups.     

Diet breadth variability in larval blue whiting as a response to plankton size structure

Diet breadth (measured as the S.D. of the log of prey size per larvae; SLH) of blue whiting micromesistius poutassou larvae followed a quadratic equation with larval size. In small larvae, diet breadth in terms of size (SLH), the mean and the maximum of the log of prey size per larvae (MLH and XLH, respectively) increased with larval size as prey size selection shifted to larger prey. In contrast, large larvae tended to reduce diet breadth of prey sizes ingested, focusing on the larger prey that were abundant, instead of raising the upper limit of prey sizes because of the low abundance of larger prey. Except for larvae at the onset of first feeding, number of prey stayed constant or decreased in relation to larval size. Both patterns (in small and large larvae) maintained a constant rate of increase of gut carbon content with increase in larval size. Large larvae appear to maintain the increase in gut carbon content during ontogenetic development by reducing diet breadth (SLH) and increasing selection towards the larger prey that are abundant.     

Ecological and evolutionary drivers of range size in Coenagrion damselflies

Geographic range size is a key ecological and evolutionary characteristic of a species, yet the causal basis of variation in range size among species remains largely unresolved. One major reason for this is that several ecological and evolutionary traits may jointly shape species' differences in range size. We here present an integrated study of the contribution of ecological (dispersal capacity, body size and latitudinal position) and macroevolutionary (species' age) traits in shaping variation in species' range size in Coenagrion damselflies. We reconstructed the phylogenetic tree of this genus to account for evolutionary history when assessing the contribution of the ecological traits and to evaluate the role of the macroevolutionary trait (species' age). The genus invaded the Nearctic twice independently from the Palearctic, yet this was not associated with the evolution of larger range sizes or dispersal capacity. Body size and species' age did not explain variation in range size. There is higher flight ability (as measured by wing aspect ratio) at higher latitudes. Species with a larger wing aspect ratio had a larger range size, also after correcting for phylogeny, suggesting a role for dispersal capacity in shaping the species' ranges. More northern species had a larger species' range, consistent with Rapoport's rule, possibly related to niche width. Our results underscore the importance of integrating macroecology and macroevolution when explaining range size variation among species.     

A process‐based model supports an association between dispersal and the prevalence of species traits in tropical reef fish assemblages

Habitat dynamics interacting with species dispersal abilities could generate gradients in species diversity and prevalence of species traits when the latter are associated with species dispersal potential. Using a process‐based model of diversification constrained by a dispersal parameter, we simulated the interplay between reef habitat dynamics during the past 140 million years and dispersal, shaping lineage diversification history and assemblage composition globally. The emerging patterns from the simulations were compared to current prevalence of species traits related to dispersal for 6315 tropical reef fish species. We found a significant spatial congruence between the prevalence of simulated low dispersal values and areas with a large proportion of species characterized by small adult body size, narrow home range mobility behaviour, pelagic larval duration shorter than 21 days and diurnal activity. Species characterized by such traits were found predominantly in the Indo‐Australian Archipelago and the Caribbean Sea. Furthermore, the frequency distribution of the dispersal parameter was found to match empirical distributions for body size, PLD and home range mobility behaviour. Also, the dispersal parameter in the simulations was associated to diversification rates and resulted in trait frequency matching empirical distributions. Overall, our findings suggest that past habitat dynamics, in conjunction with dispersal processes, influenced diversification in tropical reef fishes, which may explain the present‐day geography of species traits.     

Dispersal abilities of adult click beetles in arable land revealed by analysis of carbon stable isotopes

1 The dispersal abilities of agrioted beetles, serious pests on a variety of crops, are poorly known under natural conditions. This hampers their control. We used, for the first time, a stable isotope approach to assess dispersal of adult Agriotes obscurus in arable land.
2 After a diet switch from a C3- to a C4-plant, carbon isotope ratios of A. obscurus larvae significantly changed towards the isotopic signature of the new diet. Moreover, the larval δ¹³C signatures were transferred to the wing covers of the adult beetles with little distortion.
3 To assess the dispersal abilities under natural conditions, pheromone traps, lured for Agriotes sp., were installed at two study sites in Western Austria. Each site comprised a maize field (= C4-plant) and adjacent C3-grasslands with traps established along a transect of increasing distance to the maize.
4 δ¹³C signatures of wing covers revealed that adult male A. obscurus were able to migrate at least 80 m, which was the maximum distance that dispersal could be traced in the present study. The dispersal behaviour might have been influenced by site-specific factors.
5 The results obtained demonstrate a higher potential of adult male Agriotes to disperse than previously assumed. Moreover, the combination of pheromone trapping and stable isotope analysis proved to be an effective approach to study insect movement and dispersal in arable systems harbouring C3- and C4-crops.     

A unified framework for diversity gradients: the adaptive trait continuum

Aim Adaptive trait continua are axes of covariation observed in multivariate trait data for a given taxonomic group. These continua quantify and summarize life‐history variation at the inter‐specific level in multi‐specific assemblages. Here we examine whether trait continua can provide a useful framework to link life‐history variation with demographic and evolutionary processes in species richness gradients. Taking an altitudinal species richness gradient for Mediterranean butterflies as a study case, we examined a suite of traits (larval diet breadth, adult phenology, dispersal capacity and wing length) and species‐specific habitat measures (temperature and aridity breadth). We tested whether traits and species‐specific habitat measures tend to co‐vary, whether they are phylogenetically conserved, and whether they are able to explain species distributions and spatial genetic variation in a large number of butterfly assemblages. Location Catalonia, Spain. Methods We formulated predictions associated with species richness gradients and adaptive trait continua. We applied principal components analyses (PCAs), structural equation modelling and phylogenetic generalized least squares models. Results We found that traits and species‐specific habitat measures covaried along a main PCA axis, ranging from multivoltine trophic generalists with high dispersal capacity to univoltine (i.e. one generation per year), trophic specialist species with low dispersal capacity. This trait continuum was closely associated with the observed distributions along the altitudinal gradient and predicted inter‐specific differences in patterns of spatial genetic variability (F_ST and genetic distances), population responses to the impacts of global change and local turnover dynamics. Main conclusions The adaptive trait continuum of Mediterranean butterflies provides an integrative and mechanistic framework to: (1) analyse geographical gradients in species richness, (2) explain inter‐specific differences in population abundances, spatial distributions and demographic trends, (3) explain inter‐specific differences in patterns of genetic variation (F_ST and genetic distances), and (4) study specialist–generalist life‐history transitions frequently involved in butterfly diversification processes.     

Using biological traits to explain ladybird distribution patterns

Aim  Determining to what extent differing distribution patterns are governed by species’ life‐history and resource‐use traits may lead to an improved understanding of the impacts of environmental change on biodiversity. We investigated the extent to which traits can explain distribution patterns in the ladybird fauna (Coleoptera: Coccinellidae) of Great Britain. Location  The British mainland and inshore islands (Anglesey, the Isle of Wight and the Inner Hebrides). Methods  The distributions of 26 ladybird species resident in Britain were characterized in terms of their range size (from 2661 10‐km grid squares across Britain) and proportional range fill (at 10‐ and 50‐km scales). These were assessed relative to five traits (body length, elytral colour pattern polymorphism, voltinism, habitat specificity and diet breadth). The role of phylogenetic autocorrelation was examined by comparing the results of phylogenetic and generalized least‐squares regressions. Results  Diet breadth was the only trait correlated with range size: species with broad diets had larger range sizes than dietary specialists. Range fill was sensitive to recording intensity (a per‐species measure of the mean number of records across occupied squares); models including both recording intensity and range size provided more explanatory power than models incorporating ecological traits alone. Main conclusions  Habitat specificity is often invoked to explain the distribution patterns of species, but here we found diet breadth to be the only ecological correlate of both range fill and range size. This highlights the importance of understanding predator–prey interactions when attempting to explain the distribution patterns of predatory species. Our results suggest that the diet breadth of predatory species is a better correlate of range size and fill than other measures, such as habitat specificity.     

Range size in North American Enallagma damselflies correlates with wing size

1. Cross-species macroecological comparisons in freshwater invertebrates have been restricted by a lack of large-scale distributional data, and robust phylogenies. Here, we use data from the OdonataCentral database to explore body length–range size and wing length–range size relationships in damselflies from the genus Enallagma ; the recent publication of a phylogeny for this group meant that, as well as a cross-species analysis, we were able to assess relationships in a phylogenetically controlled manner.
2. For cross-species comparisons, only wing length showed significant (positive) regression relationships with range size and occupancy, although the inclusion of body length in multiple regressions increased the fit of the models. Damselflies with larger wings relative to their body length had larger distributions, a result confirmed by a significant positive relationship between range size and residuals from the regression of wing size on body size.
3. For the phylogenetically controlled analyses, only wing length contrast scores were significantly related to distribution patterns and entered into regression models; the significant positive relationships between wing length contrasts and both range size and occupancy contrasts suggested that evolutionary increases in wing length had occurred alongside range expansions.
4. Together these results suggest that species of Enallagma with larger wings (both absolute and relative to body length) tend to be more widely distributed in North America and that the evolution of wing size may have played a role in range expansion. No such relationships were evident for body size. We discuss the potential importance of wing morphometrics for studying the evolutionary ecology of freshwater insects.     

Range size, dispersal and niche breadth in the herbaceous flora of central England

1 It has been suggested that rare species differ from related common species in a variety of traits, including (among others) niche breadth and dispersal ability. We set out to test these ideas in the flora of central England.
2 We used two measures of range: number of hectads in Britain (national range) and number of 1 km² in a 3000-km² area of central England (local range). In each case we regressed phylogenetically independent contrasts in geographical range against contrasts in range of germination temperature (one aspect of fundamental niche breadth), terminal velocity of dispersule (a measure of wind dispersal capacity), seed weight and specialism index (a measure of the diversity of habitats exploited in central England). Seed weights and germination temperature were known for 263 species, specialism index for 261 and terminal velocity for 178.
3 Specialism index explained by far the largest part of the variance in local and national range. Seed weight, terminal velocity and germination temperature each explained only 2–4% of the variation in local range, and none of the variation in national range.
4 Most previous attempts to relate niche breadth and dispersal ability to range have concerned animals. There is little convincing published evidence for plants, and in the British herbaceous seed plants studied here the best predictor of range was diversity of habitats exploited. This pattern was independent of phylogeny.     

Crowding leads to higher incidence of brachypterous females in the tobacco thrips,Frankliniella fusca (Hinds) (Thysanoptera: Thripidae)

The effects of larval density on the wing form determination of female tobacco thrips, Frankliniella fusca, were investigated by rearing thrips on leaf disks at 27.5 °C. The developmental period, head width, body length, and forewing length of individuals in each wing morph were determined to assess the relationships among larval density, growth, and wing form. Data showed that higher rearing densities increased the production of female F. fusca brachypters. There was no consistent difference in the mean developmental periods between the two wing morphs or among all 5 density treatments. The body length of females tended to decrease with increasing rearing density, but there was no significant difference in body size between the two wing morphs when they were reared under the same density level.     

Larval food limitation in butterflies: effects on adult resource allocation and fitness

Allocation of larval food resources affects adult morphology and fitness in holometabolous insects. Here we explore the effects on adult morphology and female fitness of larval semi-starvation in the butterfly Speyeria mormonia. Using a split-brood design, food intake was reduced by approximately half during the last half of the last larval instar. Body mass and forewing length of resulting adults were smaller than those of control animals. Feeding treatment significantly altered the allometric relationship between mass and wing length for females but not males, such that body mass increased more steeply with wing length in stressed insects as compared to control insects. This may result in changes in female flight performance and cost. With regard to adult life history traits, male feeding treatment or mating number had no effect on female fecundity or survival, in agreement with expectations for this species. Potential fecundity decreased with decreasing body mass and relative fat content, but there was no independent effect of larval feeding treatment. Realized fecundity decreased with decreasing adult survival, and was not affected by body mass or larval feeding treatment. Adult survival was lower in insects subjected to larval semi-starvation, with no effect of body mass. In contrast, previous laboratory studies on adult nectar restriction showed that adult survival was not affected by such stress, whereas fecundity was reduced in direct 11 proportion to the reduction of adult food. We thus see a direct impact of larval dietary restriction on survival, whereas fecundity is affected by adult dietary restriction, a pattern reminiscent of a survival/reproduction trade-off, but across a developmental boundary. The data, in combination with previous work, thus provide a picture of the intra-specific response of a suite of traits to ecological stress.     

Dispersal ability rather than ecological tolerance drives differences in range size between lentic and lotic water beetles (Coleoptera: Hydrophilidae)

Aim In aquatic ecosystems, standing (lentic) and running (lotic) waters differ fundamentally in their stability and persistence, shaping the comparative population genetic structure, geographical range size and speciation rates of lentic versus lotic lineages. While the drivers of this pattern remain incompletely understood, the suite of traits making up the ability of a species to establish new populations is instrumental in determining such differences. Here we explore the degree to which the association between habitat type and geographical range size results from differences in dispersal ability or fundamental niche breadth in the members of the Enochrus bicolor complex, an aquatic beetle clade with species across the lentic–lotic divide. Location Western Mediterranean, with a special focus on North Africa, the Iberian Peninsula and Sicily. Methods DNA sequences for four loci were obtained from species of the E. bicolor complex and analysed using phylogenetic inference. Dispersal and establishment abilities were assessed in lentic–lotic species pairs of the complex, using flight wing morphometrics and thermal tolerance ranges as surrogates, respectively. Results There were clear differences in range size between the lotic and lentic taxa of the complex, which appears to have had a lotic origin with two transitions to standing waters. Only small differences were observed in temperature tolerance and acclimation ability between the two lotic–lentic sister species studied. By contrast, wing morphometrics revealed clear, consistent differences between lotic and lentic Enochrus species pairs, the latter having a higher dispersal capacity. Main conclusions We hypothesize that there have been two habitat shifts from lotic to lentic waters, which have allowed marked expansions in geographical range size in western Mediterranean species of the E. bicolor complex. Differences in dispersal rather than in establishment ability appear to underlie differences in geographical range extent, as transitions to lentic waters were associated with changes in wing morphology, but not in thermal tolerance range. In this lineage of water beetles, selection for dispersal in geologically short‐lived lentic systems has driven the evolution of larger range sizes in lentic taxa compared with those of their lotic relatives.     

Forecasted range shifts of arid-land fishes in response to climate change

Climate change is poised to alter the distributional limits, center, and size of many species. Traits may influence different aspects of range shifts, with trophic generality facilitating shifts at the leading edge, and greater thermal tolerance limiting contractions at the trailing edge. The generality of relationships between traits and range shifts remains ambiguous however, especially for imperiled fishes residing in xeric riverscapes. Our objectives were to quantify contemporary fish distributions in the Lower Colorado River Basin, forecast climate change by 2085 using two general circulation models, and quantify shifts in the limits, center, and size of fish elevational ranges according to fish traits. We examined relationships among traits and range shift metrics either singly using univariate linear modeling or combined with multivariate redundancy analysis. We found that trophic and dispersal traits were associated with shifts at the leading and trailing edges, respectively, although projected range shifts were largely unexplained by traits. As expected, piscivores and omnivores with broader diets shifted upslope most at the leading edge while more specialized invertivores exhibited minimal changes. Fishes that were more mobile shifted upslope most at the trailing edge, defying predictions. No traits explained changes in range center or size. Finally, current preference explained multivariate range shifts, as fishes with faster current preferences exhibited smaller multivariate changes. Although range shifts were largely unexplained by traits, more specialized invertivorous fishes with lower dispersal propensity or greater current preference may require the greatest conservation efforts because of their limited capacity to shift ranges under climate change.     

Deconstructing environmental predictability: seasonality,environmental colour and the biogeography of marine life histories

Environmental predictability is predicted to shape the evolution of life histories. Two key types of environmental predictability, seasonality and environmental colour, may influence life‐history evolution independently but formal considerations of both and how they relate to life history are exceedingly rare. Here, in a global biogeographical analysis of over 800 marine invertebrates, we explore the relationships between both forms of environmental predictability and three fundamental life‐history traits: location of larval development (aplanktonic vs. planktonic), larval developmental mode (feeding vs. non‐feeding) and offspring size. We found that both dispersal potential and offspring size related to environmental predictability, but the relationships depended on both the environmental factor as well as the type of predictability. Environments that were more seasonal in food availability had a higher prevalence of species with a planktonic larval stage. Future studies should consider both types of environmental predictability as each can strongly affect life‐history evolution.