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Fig. 3 in Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

Fig. 3. Seasonal variation of the gonadosomatic index (GSI) of Characidium pterostictum in Lajeado river, southern Brazil.

Fig. 5 in Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

Fig. 5. Boxplots comparing the total length of mature Characidium pterostictum at two sampling sites at Lajeado river (southern Brazil). PA, upstream site; PB, downstream site. Circles are outliers.

Fig. 2 in Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

Fig. 2. Boxplots comparing the total length (Lt) of Characidium pterostictum in Lajeado river (southern Brazil). PA, upstream site; PB downstream site. Numbers in parenthesis are sample size; filled circles are outliers, asterisks are extreme values, dotted line is the mean Lt.

Fig. 1 in Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

Fig. 1. Size frequency distribution (total length, Lt) for Characidium pterostictum in two sampling sites at Lajeado river, southern Brazil (PA, n = 62; PB, n = 188).

opencc-zeroNov 2022View details →

Disentangling the causes of age-assortative mating in bird populations with contrasting life-history strategies

<ol> <li>Age shapes fundamental processes related to behaviour, survival and reproduction. Where age influences reproductive success, non-random mating with respect to age can magnify or mitigate such effects. Consequently, the correlation in partners' age across a population may influence its productivity. Despite widespread evidence for age-assortative mating, little is known about what drives this assortment and its variation. Specifically, the relative importance of active (same-age mate preference) and passive processes (assortment as a consequence of other spatial or temporal effects) in driving age-assortment is not well understood.</li> <li>In this paper, we compare breeding data from a great tit and mute swan population (51- and 31-year datasets respectively) to tease apart the contributions of pair retention, cohort age-structure, and active age-related mate selection to age-assortment in species with contrasting life-histories.</li> <li>Both species show age-assortative mating, and variable assortment between years. However, we demonstrate that the drivers of age-assortment differ between the species, as expected from their life-histories and resultant demographic differences. In great tits, pair fidelity has a weak effect on age-assortative mating through pair retention; variation in age-assortment is primarily driven by fluctuations in age-structure from variable juvenile recruitment. Age-assortative mating is therefore largely passive, with no evidence consistent with active age-related mate selection. In mute swans, age-assortment is partly explained by pair retention, but not population age-structure, and evidence exists for active age-assortative pairing.</li> <li>This difference is likely to result from shorter life-spans in great tits compared to mute swans, leading to fundamental differences in their population age-structure, whereby a larger proportion of great tit populations consist of a single age-cohort. In mute swans, age-assortative pairing through mate selection may also be driven by greater age-dependent variation in fitness.</li> <li>The study highlights the importance of considering how different life-histories, and demographic differences arising from these, affect population processes that appear congruent across species. We suggest that future research should focus on uncovering the proximate mechanisms that lead to variation in active age-assortative mate selection (as seen in mute swans); and the consequences of variation in age-structure on the ecological and social functioning of wild populations.</li> </ol>

opencc-zeroFeb 2023View details →

Data from: Selection on an extreme-yet-conserved larval life-history strategy in a tapeworm

Evolutionary stasis characterizes many phenotypes, even ones that seem suboptimal. Among tapeworms, Schistocephalus solidus and its relatives have some of the shortest developmental times in their first intermediate hosts, yet their development still seems excessively long considering they can grow faster, larger, and safer in the next hosts in their complex life cycles. I conducted four generations of selection on the developmental rate of S. solidus in its copepod first host, pushing a conserved-but-counterintuitive phenotype towards the limit of known tapeworm life-history strategies. Faster parasite development evolved and enabled earlier infectivity to the stickleback next host, but low heritability for infectivity moderated fitness gains. Fitness losses were more pronounced for slow-developing parasite families, irrespective of selection line, because directional selection released linked genetic variation for reduced infectivity to copepods, developmental stability, and fecundity. This deleterious variation is normally suppressed, implying development is canalized and thus under stabilizing selection. Nevertheless, faster development was not costly; fast-developing genotypes did not decrease copepod survival, even under host starvation, nor did they underperform in the next hosts, suggesting parasite stages in successive hosts are genetically decoupled. I speculate that, on longer time scales, the ultimate cost of abbreviated development is reduced size-dependent infectivity.

Figs. 8–14 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 8–14. Genitalia morphology of Leurocephala chilensis under light microscopy: (8) male, posterior view; (9) distal end of valva, in detail (enlarged, rectangular area marked in Fig. 8); (10) aedeagus, lateral view; (11) dorsal spines of aedeagus, in detail (enlarged area indicated by seta in Fig. 10); (12) female, ventral view; (13, 14) signa, in detail (indicated by open and closed arrows in Fig. 12). Scale bars = 200, 50, 100, 20, 200, 50 and 50 µm, respectively.

Figs. 1–7 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 1–7. Adult and life-history of Leurocephala chilensis on the abaxial surface of Schinus molle leaves: (1) pinned-dried male, dorsal view; (2) egg; (3) freshly hatched first instar larva, seen by transparence within the mine (empty chorium is indicated by arrow aside); (4) middle age mine (arrow indicates the egg-chorium at the beginning of the mine; letters and associated dashed-lines correspond to the locations of tissue sections, presented in transversal view in Figs. 33–35); (5) old, empty mine (seta indicates exit of last instar larva); (6) pupal cocoon, ornamented with bubbles (arrow); (7) pupal exuvium, partially protruding from the cocoon. Scale bars = 1, 0.5, 0.5, 5, 5, 3 and 1 mm, respectively.

Figs. 27–32 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 27–32. Pupa of Leurocephala chilensis under scanning electron microscopy: (27) head, ventral view; (28) "cocoon-cutter" in detail, ventral; (29) labrum in detail, ventral; (30) sixth and seventh abdominal segments, dorsal, (31) spiracle of eighth abdominal segment, lateral; (32) last abdominal segments, dorso-posterior. Scale bars = 100, 25, 100, 100, 5 and 100 µm, respectively.

Figs. 19–26 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 19–26. Last larval instar of Leurocephala chilensis under scanning electron microscopy: (19–20) head, under dorsal and lateral views, respectively; (21) antenna, dorsal; (22) callum of first abdominal segment, ventral; (23) sternal prothoracic plate, ventral; (24) mesothoracic leg, lateral; (25) pseudopodium of fifth abdominal segment, ventral; (26) spiracle of eighth abdominal segment, lateral. Scale bars = 100, 50, 20, 50, 25, 50, 50 and 10 µm, respectively.

Figs. 15–18 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 15–18. Last instar (15, 16) and pupal (17–18) morphologies of Leurocephala chilensis under light microscopy,in dorsal and ventral views, respectively.Scale bars = 0.5 mm.

Fig. 36 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Fig. 36. Maximum likelihood phylogenetic tree of Leurocephala inferred based on 658 bp of DNA barcode sequences (cytochrome oxidase subunit I gene). Asterisk above branch indicate bootstrap support lower than 50%. Species of Spinivalva, Parectopa and Epicephala were used as outgroup; see Table 1 and text for further description.

Figs. 33–35 in A new species of Leurocephala Davis & Mc Kay (Lepidoptera, Gracillariidae) from the Azapa Valley, northern Chilean Atacama Desert, with notes on life-history

Figs. 33–35. Variation in transversal histological sections of Leurocephala chilensis on Schinus molle leaf, according to larval ontogeny; (33) first, sapfeeding instar (position indicated by letter "a" in Fig. 4); (34) early tissue-feeding instar (letter "b" in Fig. 4); (35) last tissue-feeding instar (letter "c" in Fig. 4). Ab, abaxial surface of epidermis; Ad, adaxial surface of epidermis; Lm, leaf mine; Ep, epidermis; Pp, palisade parenchyma; Sp, spongy parenchyma. Scale bars = 0.2 mm.

opencc-zeroOct 2023View details →

Data from: Distinct patterns of inheritance shape life-history traits in steelhead trout

Life-history variation is the raw material of adaptation, and understanding its genetic and environmental underpinning is key to designing effective conservation strategies. We used large-scale genetic pedigree reconstruction of anadromous steelhead trout (Oncorhynchus mykiss) from the Russian River, California, USA to elucidate sex-specific patterns of life-history traits and their heritability. SNP data from adults returning from sea over a 14-year period were used to identify 13,474 parent-offspring trios. These pedigrees were used to determine age structure, size distributions, and family sizes for these fish, as well as to estimate the heritability of two key life-history traits, spawn date and age at maturity (first reproduction). Spawn date was highly heritable (h2 = 0.73) and had a cross-sex genetic correlation near unity. We provide the first estimate of heritability for age at maturity in ocean-going fish from this species and found it to be high heritable (h2 from 0.29–0.62, depending upon sex and calculation), with a much lower genetic correlation across sexes. We also evaluated genotypes at a migration-associated inversion polymorphism and found sex-specific correlations with age at maturity. The significant heritability of these two key reproductive traits in these imperiled fish, and their patterns of inheritance in the two sexes, is consistent with predictions of both natural and sexually antagonistic selection (sexes experience opposing selection pressures). This emphasizes the importance of anthropogenic factors, including hatchery practices and ecosystem modifications, in shaping the fitness of this species, thus providing important guidance for management and conservation efforts.