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opencc-by-4.0Jul 2015View details →

Figure 2 in Early life history of the sheepnose (Plethobasus cyphyus) (Mollusca: Bivalvia: Unionoida)

Figure 2. (1–4) Plethobasus cyphyus releasing glochidia strands in raceway current. (A) mature glochidia released individually or in broken conglutinates in a clear, mucus matrix in the laboratory; (B) mucus matrix released naturally on the Chippewa River floor; (C) immature glochidia in full conglutinates (scale bar: 1 cm numbered increments); (D) glochidia sensory hair cells (at ends of arrows).

Figure 1 in Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa, Argentina

Figure 1. Location of (a) the Argentinean Pampas in South America, (b) the study site (Estancia 'Las Polvaredas', partido de Rojas, provincia de Buenos Aires; black square) in the Rolling Pampa and (c) the 39 sampling points in the study site. The map shows the land use of the year when bee sampling occurred (2010–2011 growing season). Black dots represent points located in the cropped area (n = 28), and white dots represent points located in the semi-natural area (n = 11). On each point, bees were collected with pan traps (one blue, one white and one yellow) during three 48- hour sessions.

Figure 3. A in Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa, Argentina

Figure 3. A representative sampling point in the study site, which shows three pan traps deployed in line near a wire-fence row delimiting two soybean fields (Photo: Violette Le Féon).

Figure 6 in Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa, Argentina

Figure 6. Mean number of (a) bee individuals, (b) non-Lasioglossum (Dialictus) bee individuals and (c) bee taxa per point, in cropped area (n = 28 points) and semi-natural area (n = 11 points). ns indicates a non-significant result. Asterisks indicate that means are significantly different (Wilcoxon rank sum test, *** = P <0.001). Bars show SEs.

Figure 5 in Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa, Argentina

Figure 5. Functional composition of the non-Lasioglossum (Dialictus) bee assemblage: proportion of the taxa for each life-history trait category.

Figure 11. Spheniopsis brasiliensis. A in The organs of prey capture and digestion in the miniature predatory bivalve Spheniopsis brasiliensis (Anomalodesmata: Cuspidarioidea: Spheniopsidae) expose a novel life-history trait

Figure 11. Spheniopsis brasiliensis. A transverse section through the rectum, showing minute fragments of ingested and digested prey items. AM, Amoebocyte; CIC, ciliated cell; FIPI, fragment of ingested prey item.

Figure 6. Spheniopsis brasiliensis. A in The organs of prey capture and digestion in the miniature predatory bivalve Spheniopsis brasiliensis (Anomalodesmata: Cuspidarioidea: Spheniopsidae) expose a novel life-history trait

Figure 6. Spheniopsis brasiliensis. A transverse section through the visceral mass, towards the posterior end of the stomach and illustrating the disposition of the paired gonads. APRM, Anterior septal retractor muscles; DT, digestive tubule; EO, encapsulated oocyte; FIPI, fragment of ingested prey item; GF, gonadial follicle; IPI, ingested prey item; SC, secretory cells.

Figure 2 in The organs of prey capture and digestion in the miniature predatory bivalve Spheniopsis brasiliensis (Anomalodesmata: Cuspidarioidea: Spheniopsidae) expose a novel life-history trait

Figure 2. Spheniopsis brasiliensis. The organs of the mantle cavity and visceral mass, as seen from the right side after removal of the right shell valve and mantle lobe. AAM, anterior adductor muscle; AN, anus; APRM, anterior pedal retractor muscle; ASRM, anterior septal retractor muscle; AU, auricle; CS, crystalline style; CSS, crystalline style sac; DD, digestive diverticulae; EO, encapsulated oocyte; F, foot; G, gonad; HG, hind gut; M, mouth; MG, mid gut; PAM, posterior adductor muscle; PE, pericardium; PEG, pericardial gland; PL, pallial line; PPRM, posterior pedal retractor muscle; PR, prodissoconch; PS, pallial sinus; PSRM, posterior septal retractor muscle; SE, Septum; ST, stomach.

Figure 13 in The organs of prey capture and digestion in the miniature predatory bivalve Spheniopsis brasiliensis (Anomalodesmata: Cuspidarioidea: Spheniopsidae) expose a novel life-history trait

Figure 13. Illustrations of prey capture by (A) Grippina coronata; (B) Spheniopsis brasiliensis; and (C) Cuspidaria rostrata, all drawn to approximately the same scale. (A redrawn partly after Morton et al. (2015, fig. 24 C) and C redrawn partly after Reid and Reid (1974, fig. 1). Possible prey items are also identified. The arrows show how evolution of the rostrum has allowed deeper residence of the sediments presumably for enhanced protection.

opencc-zeroAug 2020View details →

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Decoupling the effects of food and density on life history plasticity of wild animals using field experiments: Insights from the steward who sits in the shadow of its tail, the North American red squirrel

Long-term studies of wild animals provide the opportunity to investigate how phenotypic plasticity is used to cope with environmental fluctuations, and how the relationships between phenotypes and fitness can be dependent upon the ecological context. Most previous studies have only investigated life history plasticity in response to changes in temperature, yet wild animals often experience multiple environmental fluctuations simultaneously. This requires field experiments to decouple which ecological factor induces plasticity in fitness-relevant traits to better understand their population-level responses to those environmental fluctuations. For the past 32 years, we have conducted a long-term integrative study of individually marked North American red squirrels (Tamiasciurus hudsonicus Erxleben) in the Yukon, Canada. We have used multi-year field experiments to examine the physiological and life history responses of individual red squirrels to fluctuations in food abundance and conspecific density. Our long-term observational study and field experiments show that squirrels can anticipate increases in food availability and density, thereby decoupling the usual pattern where animals respond to, rather than anticipate, an ecological change. As in many other study systems, ecological factors that can induce plasticity (such as food and density) co-vary. However, our field experiments that manipulate food availability and social cues of density (frequency of territorial vocalizations) indicate that increases in social (acoustic) cues of density in the absence of additional food can induce similar life history plasticity, as does experimental food supplementation. Changes in the levels of metabolic hormones (glucocorticoids) in response to variation in food and density are one mechanism that seems to induce this adaptive life history plasticity. Although we have not yet investigated the energetic response of squirrels to elevated density or its association with life history plasticity, energetics research in red squirrels has overturned several standard pillars of knowledge in physiological ecology. We show how a tractable model species combined with integrative studies can reveal how animals cope with resource fluctuations through life history plasticity.

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Data from: Comparing life histories across taxonomic groups in multiple dimensions: how mammal-like are insects?

Explaining variation in life histories remains a major challenge because they are multi-dimensional and there are many competing explanatory theories and paradigms. An influential concept in life history theory is the 'fast-slow continuum', exemplified by mammals. Determining the utility of such concepts across taxonomic groups requires comparison of the groups' life histories in multidimensional space. Insects display enormous species richness and phenotypic diversity, but testing hypotheses like the 'fast-slow continuum' has been inhibited by incomplete trait data. We use phylogenetic imputation to generate complete datasets of seven life history traits in orthopterans (grasshoppers and crickets) and examine the robustness of these imputations for our findings. Three phylogenetic principal components explain 83-96% of variation in these data. We find consistent evidence of an axis mostly following expectations of a 'fast-slow continuum', except that 'slow' species produce larger, not smaller, clutches of eggs. We show that the principal axes of variation in orthopterans and reptiles are mutually explanatory, as are those of mammals and birds. Essentially, trait covariation in Orthoptera, with 'slow' species producing larger clutches, is more reptile-like than mammal-or-bird-like. We conclude that the 'fast-slow continuum' is less pronounced in Orthoptera than in birds and mammals, reducing the universal relevance of this pattern, and the theories that predict it.

opencc-zeroSep 2020View details →

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Famine related mortality in early life and accelerated life histories in 19th Century Belgium

Density-dependent and extrinsic mortality are predicted to accelerate reproductive maturation. The first 5 years of life is a proposed sensitive period for life-history regulation. This study examines the ways in which local mortality during this sensitive period was related to subsequent marriage timing in 19th Century Belgium (N women= 11,892; N men=14,140). Local mortality during the sensitive period was inversely associated with age at first marriage for men and women controlling for literacy, occupational status, population growth, and migration. Cox regression indicated decreased time to marriage for women (HR=1.661, 95% CI: 1.542-1.789) and men (HR=1.327, 95%CI: 1.238-1.422) from high mortality municipalities. Rising population growth rates were associated with earlier marriage for men. Migration in general was associated with later marriage for men and women. Consistent with life history predictions, harsh ecological conditions such as famine coincided with earlier marriage.

opencc-zeroOct 2020View details →

Figures 48-59 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 48-59 Hannaea inaequidentata, normal vegetative valves, LM48–59 12 valves showing diminution series, note slightly arcuate, lanceolate valve outlines, and largest valve (48) 4× longer than smallest (59).

Figures 38- 39 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 38- 39 Hannaea inaequidentata, girdle view, SEM. 38, 39 details of two apices from Fig. 36, showing epivalves and hypovalves, 4:2 configuration of girdle bands in normal but not dividing vegetative frustule (lower frustule), 4:4 configuration of girdle bands in dividing vegetative frustule (upper frustule); note two new hypovalves (arrows) are interlocked by linking spines. Scale bars: 2 μm.

Figures 40-47 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 40-47 Hannaea inaequidentata, SEM40–43 frustule details showing open girdle bands, note row of poroids interrupted at centre (42 arrow; also see Fig. 46, arrow) 44 valve with complete valvocopula 45–47 details of Fig. 44 showing open valvocopula (45 arrow), sawtooth-shaped projections attached to valve, internally visible over each virga (46 arrows; also see Fig. 41, arrows). Scale bars: 10 μm (40, 44), 2 μm (41–43, 45–47).

Figures 35-37 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 35-37 Hannaea inaequidentata, girdle view, SEM35 colony with ca. 5 frustules 36 colony with two frustules 37 detail of Fig. 1, showing epivalves and hypovalves, distinct mantle plaques, fork-shaped interlocked linking spines at valve middle (arrowheads) and more acute spines towards each apex; note 4:2 configuration of girdle bands in three normal but not dividing vegetative frustules. Scale bars: 10 μm (35, 36), 5 μm (37).

Figures 22-28 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 22-28 Hannaea cf. baicalensis, SEM. 22 complete valve, internal view, note rimoportula at each pole 23–28 detail of valve structure. Scale bars: 10 μm (22), 2 μm (23–28).

Figures 18-21 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 18-21 Hannaea cf. arcus, SEM18 complete valve with valvocopula. 19–21 details of Fig. 18, note valvocopula with sawtooth-shaped projections attached to valve (19, 20, arrows), valvocopula open at one pole (21, arrow). Scale bars: 10 μm (18), 2 μm (19–21).

Figures 131-136 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 131-136 Hannaea inaequidentata, details of pre-normal vegetative valves, internal view, SEM131, 132 two apices of Fig. 126 showing two rimoportulae per valve (two arrows) 133 middle part detail of Fig. 127 showing swollen central area and ghost striae 134 detail of Fig. 128 showing the bi-constricted middle part and ghost striae 135, 136 two apices of Fig. 130 showing two rimoportulae per valve. Scale bar: 2 μm (131–136).

Figures 125-130 from: Liu B, Williams DM (2020) From chaos to order: the life history of Hannaea inaequidentata (Lagerstedt) Genkal and Kharitonov (Bacillariophyta), from initial cells to vegetative cells. PhytoKeys 162: 81-112. https://doi.org/10.3897/phytokeys.162.56136

Figures 125-130 Hannaea inaequidentata, pre-normal vegetative valves, internal view, SEM125 twisted and rounded valve 126 arcuate valve with swollen middle part 127 valve with sternum and swollen middle part 128 valve with bi-constricted middle part and sternum 129 slightly arcuate valve with parallel middle part and sternum 130 nearly normal valve. Scale bars: 20 μm (125–130).