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opencc-zeroDec 2014View details →

Data from: Subordinate plants mitigate drought effects on soil ecosystem processes by stimulating fungi

The subordinate insurance hypothesis suggests that highly diverse communities contain greater numbers of subordinate species than less diverse communities. It has previously been reported that subordinate species can improve grassland productivity during drought, but the underlying mechanisms remain undetermined. Using a combination of subordinate species removal and summer drought, we show that soil processes play a critical role in community resistance to drought. Interestingly, subordinate species drive soil microbial community structure and largely mitigate the effect of drought on grassland soil functioning. Our results highlight subordinate species in shifting the balance within the phospholipid fatty acid (PLFA) microbial community towards more fungal dominance. Fungal communities promoted by subordinate species were more resistant to drought and maintained higher rates of litter decomposition and soil respiration. These results emphasize the important role of subordinate species in mitigating drought effects on soil ecosystem functions. Reciprocal effects between fungi and subordinate species explain also how subordinate species better resisted to drought conditions. Our results point to a delayed plant–soil feedback following environmental perturbation. Additionally, they extend the diversity insurance hypothesis by showing that more diverse communities not only contain species well adapted to perturbations, but also species with higher impacts on soil microbial communities and related ecosystem functions.

opencc-zeroDec 2017View details →

Data from: Subordinate females in the cooperatively breeding Seychelles warbler obtain direct benefits by joining unrelated groups

1. In many cooperatively breeding animals, a combination of ecological constraints and benefits of philopatry favours offspring taking a subordinate position on the natal territory instead of dispersing to breed independently. However, in many species individuals disperse to a subordinate position in a non-natal group ("subordinate between-group" dispersal), despite losing the kin-selected and nepotistic benefits of remaining in the natal group. It is unclear which social, genetic and ecological factors drive between-group dispersal. 2. We aim to elucidate the adaptive significance of subordinate between-group dispersal by examining which factors promote such dispersal, whether subordinates gain improved ecological and social conditions by joining a non-natal group, and whether between-group dispersal results in increased lifetime reproductive success and survival. 3. Using a long-term dataset on the cooperatively-breeding Seychelles warbler (Acrocephalus sechellensis), we investigated how a suite of proximate factors (food availability, group composition, age and sex of focal individuals, population density) promote subordinate between-group dispersal by comparing such dispersers with subordinates that dispersed to a dominant position or became floaters. We then analysed whether subordinates that moved to a dominant or non-natal subordinate position, or became floaters, gained improved conditions relative to the natal territory, and compared fitness components between the three dispersal strategies. 4. We show that individuals that joined another group as non-natal subordinates were mainly female and that, similar to floating, between-group dispersal was associated with social and demographic factors that constrained dispersal to an independent breeding position. Between-group dispersal was not driven by improved ecological or social conditions in the new territory and did not result in higher survival. Instead, between-group dispersing females often became co-breeders, obtaining maternity in the new territory, and were likely to inherit the territory in the future, leading to higher lifetime reproductive success compared to females that floated. Males never reproduced as subordinates, which may be one explanation why subordinate between-group dispersal by males is rare. 5. Our results suggest that subordinate between-group dispersal is used by females to obtain reproductive benefits when options to disperse to an independent breeding position are limited. This provides important insight into the additional strategies that individuals can use to obtain reproductive benefits.

opencc-zeroDec 2013View details →

Data from: Genetic sorting of subordinate species in grassland modulated by intraspecific variation in dominant species.

Genetic variation in a single species can have predictable and heritable effects on associated communities and ecosystem processes, however little is known about how genetic variation of a dominant species affects plant community assembly. We characterized the genetic structure of a dominant grass (Sorghastrum nutans) and two subordinate species (Chamaecrista fasciculata, Silphium integrifolium), during the third growing season in grassland communities established with genetically distinct (cultivated varieties or local ecotypes) seed sources of the dominant grasses. There were genetic differences between subordinate species growing in the cultivar versus local ecotype communities, indicating that intraspecific genetic variation in the dominant grasses affected the genetic composition of subordinate species during community assembly. A positive association between genetic diversity of S. nutans, C. fasciculata, and S. integrifolium and species diversity established the role of an intraspecific biotic filter during community assembly. Our results show that intraspecific variation in dominant species can significantly modulate the genetic composition of subordinate species.

FIGURE 4 in A taxonomic revision of order Pilisuctorida (Ciliophora, Apostomatia) with keys to the subordinate taxa

FIGURE 4. Conidophryid ciliates found in Ukraine and Mexico. A—individual of Conidophrys fucatum at the seta of Gammarus balcanicus (Ukraine; ×640); B—division individual of C. fucatum at the seta of G. aequicauda (Ukraine; ×640); C—individual of C. fucatum at the short seta of Gammarus balcanicus (Ukraine; ×640); D—individual of C. fucatum at the seta of Hyalella azteca (Mexico; ×400); E—C. enkystotrophos at short seta of Echinogammarus olivii (Ukraine, ×640); F—C. pіtelkae at the seta of Litopenaeus setiferus (Mexico; ×400).

FIGURE 3 in A taxonomic revision of order Pilisuctorida (Ciliophora, Apostomatia) with keys to the subordinate taxa

FIGURE 3. The life cycles of ciliates from genera Conidophrys and Ascophrys after different authors. A—trophont of Conidophrys with two tomites; B—emerged tomite of Conidophrys; C—Conidophrys' tomite attached to seta; D—lacrymoid stage of Conidophrys' trophont development; E—spheroid stage of Conidophrys; F, G—cucurbitoid stages of Conidophrys; H—frontal view of Ascophrys rodor zenithal tomite; I—frontal view of nadiral tomite (m—macronucleus; o. f.—adhesive organelle); J—phoront stage in circular cyst; K—the early stage of trophont development; L—trophont stage; M—the development of trophont to tomont (propagative trophont) stage; N—tomitogenesis; O—the hatching of tomites; P—the field of trophont primordial ciliature; Q—the primary anlage of infraciliature in young tomont; R—multiplication of infraciliature anlages before tomitogenesis (stage M); S and T—two sequential phases of tomite infraciliature morphogenesis (a—"narrowed field; b—"ampliate field). (A–G—modified from Chatton and Lwoff 1936; H–T—modified from Campillo and Deroux 1974).

FIGURE 2 in A taxonomic revision of order Pilisuctorida (Ciliophora, Apostomatia) with keys to the subordinate taxa

FIGURE 2. Ciliates of genera Askoella and Ascophrys described by different authors. A—ventral side of Askoella janssoni; B—dorsal side of A. janssoni (scale bar 10 µm); C—macronucleus morphology of A. janssoni; D—A. heliostoma; E—trophont of Ascophrys rodor: F—phoront of Ascophrys rodor (A–C—modified from Fenchel, 1965; D—modified from Jankowski 1967b; E-F—modified from Deroux, Campillo and Bradbury, 1975).

FIGURE 1 in A taxonomic revision of order Pilisuctorida (Ciliophora, Apostomatia) with keys to the subordinate taxa

FIGURE 1. Ciliates of genus Conidophrys described by different authors. A—Mycodinium fucatum; B—trophont of Conidophrys pilisuctor; C—tomite of C. pilisuctor (lateral view); D—individual at the short seta of Jassa falcata; Eindividual of C. guttipotor at the short seta of Sphaeroma serratum; F—individual at the host non-secretory seta; G—trophont of Conidophrys sp. from Jaera albifrons with developing tomites (Mac—macronucleus; Mic—micronucleus; Cytcytopharynx): H—cucurbitoid stage of developing trophont from J. albifrons; I—the stalk and its base; J—Conidophrys enkystotrophos; K—trophont of C. pіtelkae, left lateral view; L—trophont of C. pіtelkae, right lateral view; M—young trophont of C. pіtelkae; N—ventral view of C. pіtelkae tomite (X—tube; Cy—cytostome). (A—modified from Averinzeff 1916: B-F—modified from Chatton and Lwoff 1936; G-I—modified from Jones and Khan 1970; J—modified from Jankowski 1972; K-N—modified from Bradbury 1975).

FIGURE 5. A–F in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 5. A–F. Pteridium esculentum subsp. arachnoideum var. paedomorficum: A. pinnae (Schwartsburd 3844), B. segment, abaxially (Schwartsburd 3844), C. segment, cross section, abaxial side up, showing sericeous veins, with with lax, arachnoid hairs, and glabrous laminar tissue between the veins (Schwartsburd 3844), D. segment, abaxially (Schwartsburd 3844), E. segment, cross section, abaxial side up, showing veins with setose hairs, and glabrous laminar tissue between the veins, F–H. Pteridium esculentum subsp. arachnoideum × P. esculentum subsp. campestre: F. pinnule (Fay 2413), G. segment, abaxially (Guedes 14217), H. segment, cross section, abaxial side up, showing strigose veins, with with stiff, acicular hairs, and laminar tissue between the veins with farinaceous appearance, fully covered by gnarled hairs (Guedes 14217). Drawn by R. Pinto.

FIGURE 4 in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 4. Distribution of Pteridium esculentum subsp. gryphus var. gryphus (blue circles) and P. esculentum subsp. gryphus var. harpianum (yellow circles) in South America.

FIGURE 1. A–C in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 1. A–C. Pteridium esculentum subsp. campestre: A. pinnule (Nonato 927), B. segment, abaxially (Schwartsburd 2411), C. segment, cross section, abaxial side up, showing strigose veins, with stiff, acicular hairs, and laminar tissue between the veins with farinaceous appearance, fully covered with gnarled hairs (Schwartsburd 2411), D–F. Pteridium esculentum subsp. arachnoideum var. arachnoideum: D. pinnule (Schwartsburd 2490), E. segment, abaxially (Schwartsburd 2490), F. segment, cross section, abaxial side up, showing serieceous veins, with lax, arachnoid hairs, and glabrous laminar tissue between the veins (Schwartsburd 2490). "s.d.s.": simple distal segments, "c.d.s.": compound distal segments. Drawn by R. Pinto, reproduced from Schwartsburd et al. (Phytotaxa 170(2): 105. 2014).

FIGURE 3. A–C in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 3. A–C. Pteridium esculentum subsp. gryphus var. gryphus: A. pinnule (Gleason 423), B. segment, abaxially (Gleason 423), C. segment, cross section, abaxial side up, showing sericeous veins, with lax, arachnoid hairs, and laminar tissue between the veins with farinaceous appearance, fully covered by gnarled hairs (Gleason 423), D–F. Pteridium esculentum subsp. gryphus var. harpianum: D. pinnule ("B.W." 1121 [US-2019769]), E. segment, abaxially (Barreto 1623), F. segment, cross section, abaxial side up, showing veins abaxially nearly glabrous, and laminar tissue between the veins with farinaceous appearance, fully covered by gnarled hairs (Barreto 1623). Drawn by R. Pinto.

FIGURE 2 in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 2. Distribution of Pteridium esculentum subsp. arachnoideum (red circles), P. esculentum subsp. campestre (green circles), and P. esculentum subsp. gryphus (blue circles) in South America.

FIGURE 7 in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 7. Distribution of Pteridium esculentum subsp. arachnoideum (red circles), P. esculentum subsp. campestre (green circles), and P. esculentum subsp. arachnoideum × P. esculentum subsp. campestre (gray circles) in South America.

FIGURE 6 in Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l. -Dennstaedtiaceae), based on morphology and geography

FIGURE 6. Distribution of Pteridium esculentum subsp. arachnoideum var. arachnoideum (red circles) and P. esculentum subsp. arachnoideum var. paedomorficum (purple circles) in South America.

opencc-zeroMay 2023View details →

Data from: Pregnancy reduces concurrent pup care behaviour in meerkats, generating differences between dominant and subordinate females

In some mammals, and particularly in cooperative breeding ones, successive bouts of reproduction can overlap so that a female is often pregnant while still nurturing dependent young from her previous litter. Such an overlap requires females to divide their energetic budget between two reproductive activities, and pregnancy costs would consequently be expected to reduce investment in concurrent offspring care. However, explicit evidence for such reductions is scarce, and the potential effects they may have on work division in cooperative breeders have not been explored. Using 25 years of data on reproduction and cooperative behaviour in wild Kalahari meerkats, supplemented with field experiments, we investigated whether pregnancy reduces contributions to cooperative pup care behaviours, including babysitting, provisioning, and raised guarding. We also explored whether pregnancy, which is more frequent in dominants than subordinates, could account for the reduced contributions of dominants to the cooperative pup care behaviours. We found that pregnancy, particularly at late stages of gestation, reduces contributions to cooperative pup care; that these reductions are eliminated when the food available to pregnant females is experimentally supplemented; and that pregnancy effects accounted for differences between dominants and subordinates in two of the three cooperative behaviours examined (pup provisioning and raised guarding but not babysitting). By linking pregnancy costs with reductions in concurrent pup care, our findings illuminate a tradeoff between investment in successive, overlapping bouts of reproduction. They also suggest that some of the differences in cooperative behaviour between dominant and subordinate females in cooperative breeding mammals can be a direct consequence of differences in their breeding frequency.