Oceanographic-related variation in the bone sizes of extinct great auks

Reviewed by: The Tragic Tale of the Great Auk Elizabeth Bush Thornhill, Jan The Tragic Tale of the Great Auk; written and illus. by Jan Thornhill. Groundwood, 2016 44p ISBN 978-1-55498-865-5 $18.95 R* Gr. 3-6 The short of it is that the great auk, a flightless seabird, is extinct. The long of it, however, is that the story of this extinction is one of considerable complexity, with plot threads involving evolution, geology, human history, and several strokes of plain bad luck. Thornbill’s approach to this historical event is so advanced it’s simple: she tells the tale. No chapter headings, no sidebars, no highlighted vocabulary, no literary gimmicks. She just tells the tale. And what a tale it is. Evolution favored the great auk with a body wonderfully adapted to hunting fish in the cold, open sea. With short wings, and legs set unusually far back, it was a speedy, agile swimmer. The trade-off, though, was the inability to fly, and since birds cannot lay eggs in mid ocean, auks were forced ashore to mate, lay their eggs, and rear their fledglings in an environment in which their only mobility was an awkward waddle. Fortunately the great auk always managed to find nesting grounds on storm-wracked North Atlantic coasts, on uninhabitable islands, or in any number of craggy, cliff-protected spots that foiled predators or at least limited the predators’ threat to their overall numbers. Even early humans, who are known to have developed a taste for great auk, couldn’t make a dent in their thriving populations. Once human hunters took to the sea in ever more efficient boats, though, auk colonies began to diminish and even disappear, losing the race to find protected nesting grounds. Was this the beginning of the tragic end? Or was it when the last excellent rocky island refuge sank in a volcanic eruption? Or when legal efforts to protect the endangered birds against hunters proved too little, too late? Or when the great auk’s rarity made it a target for collectors, who hustled the very last survivors to their demise in the nineteenth century ? Thornhill engages readers with well-placed questions that anticipate their curiosity. “So why didn’t The Wobble [an New England nickname for the Great Auk] avoid land entirely?” “How, then, did it successfully raise its young for millennia?” “So is that all that’s left of the Great Auk? A few sad taxidermy displays and blown eggs?” She also exploits the natural momentum of the auks’ history: as the tale shifts chronological scale from evolutionary time to the historical time, the pacing accelerates and the details become more plentiful and sharply focused. Humans appear on the scene, and we learn about the tempting richness of auk egg omelettes and pancakes; the usefulness of a fatty auk carcass as a substitute for firewood; the execution of the last known auk in the British Isles for witchcraft; the skyrocketing value of rare auk eggs that drove a collector to crush one specimen in order to raise the value of another; Iceland’s 1971 purchase of a stuffed auk and its [End Page 111] celebratory arrival: “A bird that never flew in life flew into Iceland strapped into its very own seat on an airplane.” Digital artwork, which makes clever use of fine white lines detailing foamy ocean and ghostly images of the decimated species, could easily pass for mixed-media compositions. In keeping with the great auk’s very long backstory and relatively short but deadly connection with mankind, most spreads feature auks in the wild rather than alongside their human predators. A notable trio, though, delivers serious chills: a museum gallery featuring a pair of taxidermied auks; the stuffed auk on its way to Iceland, seen through an airplane window; and a view of the booted legs of the men who strangled the last remaining auks, which now dangle at the hunters’ sides. Yes, Nature dealt the great auks some weak hands, but they beat the odds for countless millennia, until humans finally drove them from the table. Lists of resources, references, extinct species, and great auk names in thirteen...

Body size of many animals varies with latitude: body size is either larger at higher latitudes (Bergmann’s rule) or smaller at higher latitudes (converse Bergmann’s rule). However, the causes underlying these patterns are poorly understood. Also, studies rarely explore how sexual size dimorphism varies with latitude. Here we investigate geographic variation in body size and sexual size dimorphism of the seed‐feeding beetle Stator limbatus, collected from 95 locations along a 38° range in latitude. We examine 14 variables to test whether clines in environmental factors are adequate to explain geographic patterns of body size. We found that body size and sexual size dimorphism of S. limbatus varied considerably with latitude; beetles were smaller but more dimorphic at lower latitudes. Body size was not correlated with a gradient in mean temperature, contrary to the commonly accepted hypothesis that clines are produced by latitudinal gradients in temperature. Instead, we found that three factors were adequate to explain the cline in body size: clinal variation in host plant seed size, moisture (humidity), and seasonality (variance in humidity, precipitation, and temperature). We also found that the cline in sexual size dimorphism was partially explainable by a gradient in moisture, though moisture alone was not sufficient to explain the cline. Other ecological or environmental variables must necessarily contribute to differences in selection on male versus female body size. The main implications of our study are that the sexes differ in the magnitude of clinal variation in body size, creating latitudinal variation in sexual size dimorphism, and that clines in body size of seed beetles are likely influenced by variation in host seed size, water availability, and seasonality.

Body size of many animals varies with latitude: body size is either larger at higher latitudes (Bergmann's rule) or smaller at higher latitudes (converse Bergmann's rule). However, the causes underlying these patterns are poorly understood. Also, studies rarely explore how sexual size dimorphism varies with latitude. Here we investigate geographic variation in body size and sexual size dimorphism of the seed-feeding beetle Stator limbatus, collected from 95 locations along a 38 degrees range in latitude. We examine 14 variables to test whether clines in environmental factors are adequate to explain geographic patterns of body size. We found that body size and sexual size dimorphism of S. limbatus varied considerably with latitude; beetles were smaller but more dimorphic at lower latitudes. Body size was not correlated with a gradient in mean temperature, contrary to the commonly accepted hypothesis that clines are produced by latitudinal gradients in temperature. Instead, we found that three factors were adequate to explain the cline in body size: clinal variation in host plant seed size, moisture (humidity), and seasonality (variance in humidity, precipitation, and temperature). We also found that the cline in sexual size dimorphism was partially explainable by a gradient in moisture, though moisture alone was not sufficient to explain the cline. Other ecological or environmental variables must necessarily contribute to differences in selection on male versus female body size. The main implications of our study are that the sexes differ in the magnitude of clinal variation in body size, creating latitudinal variation in sexual size dimorphism, and that clines in body size of seed beetles are likely influenced by variation in host seed size, water availability, and seasonality.

This paper presents all available archaeozoological, ethnohistorical, and historical evidence on the Great Auk, Pinguinus impennis (L.), in Greenland. Substantial new contributions are: (1) the presentation of 132 Auk bones from seven archaeological sites, and (2) a translation of Otto Fabricius's original handwritten notes on the Great Auk in Greenland. A description of the Greenlandic Great Auk's zoogeography and biology is given as well as a description of the Inuit's Great Auk hunting methods and of their use of Great Auk products. Main conclusions are: (1) P. impennis probably occurred further north in Greenland c. 2000 BC than in historical times; (2) c. 1500 BC P. impennis possibly nested in West Greenland; (3) Between 1350 and 1800 AD Great Auks originating from breeding colonies near Newfoundland or Iceland wintered on the banks off West Greenland from Cape Farewell in the south to Maniitsoq in the north; (4) Great Auks were breeding in Southwest Greenland in small numbers in the 1760's and 1770'...

Body size is an integrative trait with substantial fitness consequences in animals. Geographical clines in body size have fascinated biologists because of their potential to provide insight into the mechanisms governing local adaptation and phenotypic plasticity. In this complex study, we focused on variation in body size of Silpha carinata (Coleoptera: Silphidae) along elevation gradients in Central Europe. Altitudinal clines were investigated separately for males and females as sex‐specific responses to environmental conditions are documented for a variety of insect species. To identify potential underlying mechanisms responsible for observed patterns, a common garden experiment and investigation of within‐population variation in body size were performed. Body size of S. carinata recorded in nature sharply decreased with increasing altitude in both genders, whereas sexual size dimorphism did not change with altitude. The degree of within‐population variation in body size recorded in nature did not change with altitude. Under standardized laboratory conditions, higher altitude females produced smaller eggs than those from lower altitude. This size difference persisted to the very end of the larval period. Unfortunately, only few offspring survived till adulthood in the laboratory and thus precise analysis of offspring adult sizes was unfeasible, but between‐population differences in body size seems to persist to adulthood. The observed converse Bergmann's cline in S. carinata fits well with what has been predicted for large, carnivorous, univoltine insect species. Until now, investigation of within‐population variation in body size is rare in insects, and future complementary studies focused on this issue are highly needed as within‐population variation could explain body size patterns observed at between‐population level.

Bergmann's rule states that, among conspecific populations, individuals are larger in cooler than in warmer environments as a consequence of selection related to heat conservation. Many of the most comprehensive assessments of Bergmann's rule to date have examined clinal patterns in body size among species assemblages. Our study is a more direct test of Bergmann's rule because we examine the pattern within a single, widely distributed species. We examined geographic variation in body and cell size in the spotted turtle ( Clemmys guttata). Our analysis of 818 turtles collected from the entire range (45-28 degrees N), indicated that body size increased with latitude; however, the relationship was driven by a population of large turtles at the northern extreme of the species' range. When the northern population was removed from the analyses, Bergmann's rule was not supported, and the smallest turtles occurred near the central part of the species' distribution. Recent literature has suggested that latitudinal clines in body size may simply be a physiological byproduct of the effects of temperature on cell division, resulting in larger cells, and hence larger organisms, from cooler temperatures. Measurements of the diameter of skin cells did not support the hypothesis that cell size increases with latitude and decreases with temperature in the spotted turtle, nor was there a significant relationship between body size and cell size. Our study suggests that neither Bergmann's rule nor cell size variation sufficiently explain the body size cline observed in the spotted turtle. We hypothesize that patterns in body size are related to variation in female size at maturity and reproductive cycles.

Summary Aim Geographic variation in body size and heterozygosity were surveyed for discrete populations of the ant lion, Myrmeleon immaculatus DeGeer, collected from the central and northeastern United States. LocationCollection sites were located in the central and eastern United States ranging from western Oklahoma to northern New York. Methods We collected 872 M. immaculatus larvae from thirty‐four collecting sites. At each site, we randomly sampled ant lion pits and collected between fifteen and fifty‐two larvae in total. Larvae were preserved in 95% ETOH for morphological analysis and frozen in a −80°C freezer for protein electrophoresis. We measured the body size of eighty‐five preserved adult M. immaculatus obtained from museum collections using head width as an indicator of body size. Five enzymes [GPI (glucose phosphate isomerase), MDH (malate dehydrogenase), PEP (peptidase), DIA (diaphorase) and SOD (superoxide dismutase)] were used in the heterozygosity analyses. Results Larval and adult body size increased with latitude, but decreased with elevation. Average heterozygosity, measured at five polymorphic loci, also increased significantly with latitude. Minimum temperature variance was the best predictor of body size, whereas precipitation and maximum temperature were the best predictors of heterozygosity. Populations were genetically differentiated from one another and showed a pattern of isolation by distance, as measured by Wright's Fst values and Nei's genetic distances. Main conclusions Sampling artifacts, heat conservation, character displacement, cell‐size variation, density‐dependent mortality, and differential dispersal probably cannot account for latitudinal variation in ant lion body size. Our results implicate the importance of diurnal photoperiod, which varies with latitude, but not with elevation. Because photoperiod often controls growth, diapause, and metamorphosis, it may be an important determinant of latitudinal clines in body size and life history of insects.

A wide variety of animals show latitudinal cline in body size, which can be caused not only by abiotic factors such as temperature but also by biotic ones such as diet quality. In seed feeding insects, adult body size is affected by seed size. Therefore, seed size may be an important factor to explain the latitudinal cline in body size if the seed size also shows a latitudinal cline. In the present study, we detected a latitudinal cline in body size of an alien bruchid, Acanthoscelides pallidipennis, which was introduced into Japan from North America with its host plant Amorpha fruticosa. In 13 out of 24 populations that we collected in Japan, A. fruticosa seeds were infested with A. pallidipennis. Both body size of A. pallidipennis and host seed weight increased with latitude in the infested populations, but not in the non‐infested populations. There was a significant positive correlation between body size and seed weight in both field observation and laboratory experiment. In a common environmental condition, there was no significant difference in body size among three latitudinally different populations. Our results show that the latitudinal cline in adult body size of A. pallidipennis across a non‐native range could be explained by the latitudinal cline in seed weight of A. fruticosa, but not by genetic differentiation among populations.

Seabirds are the most threatened of any living group of birds, continuing a larger pattern of elevated Holocene bird extinctions on islands and coastlines. The Great Auk (Charadriiformes: Pinguinus impennis) was found on both coasts of the Atlantic during the Holocene until its last sighting on Iceland in 1844. Far more is known about the population structure and genetic diversity of NE Atlantic populations, and the latest surviving populations were documented from the British Isles in 1834. While sightings from Canada suggest Great Auks disappeared by 1800, no systematic evaluation of extinction timing has been conducted for this coast. Determining extinction timing of the Great Auk in Maine allows a comparison to be made to populations in other areas of the Atlantic Ocean, and raises the question: was the Maine population’s fate different due to regional, cultural, or other factors? There is a single eye-witness record in the late 17th century at “Black Point”, now Scarborough, Maine. To address this gap, we compiled a radiocarbon dataset on associated material from Maine archaeological shell middens. These 91 dates from 13 sites situate the Great Auk in Maine from about 180 to 4,555 years before present. The majority of these dates are from charcoal samples, but also include shells, ceramics, and bone, and cultural contexts span the Middle and Late Ceramic Periods. To account for differences in stratigraphic control and sampling material, we assigned quality scores, and used these scores to run a sensitivity analysis in extinction timing with the GRIWM model. Disentangling the spatiotemporal dynamics of the Great Auk extinction in Maine is useful in determining how to conserve current species in decline and modern insular seabirds in Maine, such as the puffin. Future study will include new radiocarbon dating of bones as well as isotopic and morphometric analysis to unfold more chapters of the Maine Great Auk’s narrative.

Species with widespread distributions frequently show clines in body size across broad geographic areas. These clines may be the result of “ecogeographical rules” that describe spatial patterns of phenotypic differences driven by environmental variation. Intraspecific variation in body size, and the mechanisms causing this variation, have been poorly described in social wasps. This study examined ecogeographical patterns of body size for 12 native species and one non-native species of North American paper wasps (genus: Polistes) using body size measurements from > 14,000 pinned museum specimens. Intraspecific body size was correlated with latitude, elevation, and broadscale climate variation. However, the direction of this relationship was idiosyncratic across species, with Bergmann’s clines and converse Bergmann’s clines equally represented. There was no evidence of a phylogenetic signal in the direction of the cline between body size and the environment. Within species, the worker caste and the reproductive caste showed the same direction of response between body size and latitude, although for most species the reproductive caste was larger than the worker caste. Intraspecific variation in body size appears to be driven by differences in the response among species to similar environmental variables but the mechanisms causing this variation remain unknown.

Background. Large-scale patterns of body size variation have occupied biologists for over a century, yet the causes of some of these patterns remain elusive. Bergmann’s rule is a classical eco-geographic rule that relates body size of homoiothermal animals with environmental temperature (or latitude). Contemporary data indicate that latitudinal clines in body size, predicted by Bergmann’s rule also exist in ectothermic organisms and in some groups appear to be fairly common. Despite plenty of data from literature on latitudinal intraspecific body size variation in insects are scarce and in Ground Beetles are absent at all. The aim of this research was to: (i) model the effect of the region of habitation into the body size variation in widespread carabid species; (ii) describe body size variation of mentioned species in latitudinal gradient. Materials and methods. The design of our study was organized as follows: (1) we study the intraspecific variation of body size in carabids, bearing in mind that closely related species could act very differently, each individual species following or countering Bergmann's Rule in its own way; (2) in all studied species the same six traits were measured; (3) we used linear models to isolate concretely latitude effects (but not another environmental factors) to traits variation; (4) beetles were sampled in the same space over the vast regions covering their ranges. Six carabid species from different regions of Russia were analyzed. Linear models were applied to quantify contribution of region’s latitude where beetles had been sampled into that variation. We applied voice-counting method to reveal trends of traits size variation in latitude gradient and relative warp analysis (a principal component analysis of the weight matrix) when analyzing effect of latitude on body shape shifts in studied species of carabids. Results. Different traits of certain species varied in differing ways under the influence of the same environmental factor. Contribution of latitude into the traits variation was not similar in studied species. The compiled data over the all six traits variation in latitude gradient in each species showed that C. granulatus followed Bergmann's rule, P. cupreus – converse Bergmann's rule, in C. cancellatus, C. hortensis and P. melanarius the number of cases which followed direct Bergmann's clines, converse ones and non-significant shifts were equal, P. niger - didn't show any clines at all. Nevertheless the separate analysis of the only elytra length variation showed that in three Carabus species and P. niger elytra length decreased towards the high latitudes, P. melanarius demonstrated saw-tooth elytra length variation in latitude gradient and Poec. cupreus – the counter-gradient one. Conclusion . Explanation that takes into account the natural history, climatic correlations and sexual size dimorphism is needed to assess the observed contrasting geographic patterns and differences between species, morphometric traits and sexes, since size clines (e.g. Bergmannian clines) may obey to multiple selection pressures that are not only dependent on temperature constraints but also on other climatic and biotic factors that could influence body size. Key words: carabids, environmental factors, voice-counting method, converse Bergman clines, saw-tooth variation, counter-gradient variation, linear models.

Body size of insects with flexible life cycles is expected to conform to the saw‐tooth model, a model in which the relationship between size and developmental time depends on length of the growing season. In species with high variability in terms of voltinism, however, more complex patterns can be expected. Few empirical studies have demonstrated the existence of such relationships, or whether climatic factors contribute to these relationships. In this study, we investigated the geographic variation in body size of the Chinese cockroach, Eupolyphaga sinensis Walker (Blattaria: Polyphagidae), which has a variable life cycle length. The sizes of adults – collected from 14 localities ranging from temperate to subtropical zones in China – were measured, using body length, body width, and pronotum width as parameters. The relationship between size, latitude, and climate factors (encompassing 10 variables) was then investigated. We found that the body size of E. sinensis varied considerably with latitude: cockroaches were larger at low and high latitudes, but smaller at intermediate latitudes. Thus, the relationship between climate and body size conformed to a saw‐tooth pattern. Results indicate that two factors were significantly associated with body size clines: season length and variability in life cycle length. Our results also demonstrated that climatic factors contribute to latitudinal clines in body size, which has important ecological and evolutionary implications. It can be expected that global climate change may alter latitudinal clines in body size of E. sinensis.

Clinal variation in body size and sexual dimorphism in an Indian fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae)

Geographic variation in body size and sexual dimorphism of the short-nosed fruit bat (Cynopterus sphinx) was investigated in peninsular India. Bats were sampled at 12 localities along a 1200 km latitudinal transect that paralleled the eastern flanks of the Western Ghats. The geographic pattern of variation in external morphology of C. sphinx conforms to the predictions of Bergmann's Rule, as indicated by a steep, monotonic cline of increasing body size from south to north. This study represents one of the first conclusively documented examples of Bergmann's Rule in a tropical mammal and confirms that latitudinal clines in body size are not exclusively restricted to temperate zone homeotherms. Body size was indexed by a multivariate axis derived from principal components analysis of linear measurements that summarize body and wing dimensions. Additionally, length of forearm was used as a univariate index of structural size to examine geographic variation in a more inclusive sample of bats across the latitudinal transect. Multivariate and univariate size metrics were strongly and positively correlated with body mass, and exhibited highly concordant patterns of clinal variation. Stepwise multiple regression on climatological variables revealed that increasing size of male and female C. sphinx was associated with decreasing minimum temperature, increasing relative humidity, and increasing seasonality. Although patterns of geographic size variation were highly concordant between the sexes, C. sphinx also exhibited a latitudinal cline in the magnitude and direction of sexual size dimorphism. The size differential reversed direction across the latitudinal gradient, as males averaged larger in the north, and females averaged larger in the south. The degree of female-biased size dimorphism across the transect was negatively correlated with body size of both sexes. Canonical discriminant analysis revealed that male- and female-biased size dimorphism were based on contrasting sets of external characters. Available data on geographic variation in the degree of polygyny in C. sphinx suggests that sexual selection on male size may play a role in determining the geographic pattern of sexual size dimorphism.

SummaryThe tendency of ectotherms to get larger in the cold (Bergmann clines) has potentially great implications for individual performance and food web dynamics. The mechanistic drivers of this trend are not well understood, however. One fundamental question is to which extent variation in body size is attributed to variation in cell size, which again is related to genome size. In this study, we analyzed body and genome size in four species of marine calanoid copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Paraeuchaeta norvegica, with populations from both south Norwegian fjords and the High Arctic. The Calanus species showed typical interspecific Bergmann clines, and we assessed whether they also displayed similar intraspecific variations—and if correlation between genome size and body size differed between species. There were considerable inter‐ as well as intraspecific variations in body size and genome size, with the northernmost populations having the largest values of both variables within each species. Positive intraspecific relationships suggest a functional link between body and genome size, although its adaptiveness has not been settled. Impact of additional drivers like phylogeny or specific adaptations, however, was suggested by striking divergences in body size – genome size ratios among species. Thus, C. glacialis and C. hyperboreus, had fairly similar genome size despite very different body size, while P. norvegica, of similar body size as C. hyperboreus, had the largest genome sizes ever recorded from copepods. The inter‐ and intraspecific latitudinal body size clines suggest that climate change may have major impact on body size composition of keystone species in marine planktonic food webs.