Spatial distribution of resting stages,rate of emergence from diapause and times to adulthood and to the appearance of the first clutch in 3 species of cyclopoid copepods

The spatial distribution of dormant copepodids of 3 species of cyclopoid copepods — Cyclops vicinus, Mesocyclops leuckarti and Thermocyclops crassus — was studied in 4 small lakes in South Germany. The rate of emergence from diapause and times from the resting stage to adulthood and from adulthood to the appearance of the first clutch was studied at 4 constant temperatures (5, 10, 15, 20 °C) in the laboratory. Resting stages of C. vicinus were always concentrated in the deepest parts of the lakes and were found relatively deep in the mud. M. leuckarti- and T. crassus-copepodids preferred shallow areas in deep lakes but were concentrated in the deep areas in shallow lakes. Copepodids of both species were always concentrated in the uppermost mud layers.Rate of emergence from diapause was strongly temperature-dependent. At high temperatures (20 °C) copepodids of all species under study emerged within 2 weeks. At lower temperatures C. vicinus copepodids showed the highest rate of emergence. At 5 to 10 °C only few M. leuckarti- and T. crassus-copepodids had emerged after the investigation period (7 weeks). Both C. vicinus and T. crassus showed the highest rate of emergence at the natural end of diapause but even at that time only few T. crassus-copepodids emerged at 5 °C. Times to adulthood at 5 °C were shortest in C. vicinus. At higher temperatures this species was passed by M. leuckarti. Times from adulthood to the appearance of the first clutch at 5–15 °C were shortest in C. vicinus. T. crassus produced no clutch at 5 and 10 °C.     

Molecular evidence for Gondwanan origins of multiple lineages within a diverse Australasian gecko radiation

Aim Gondwanan lineages are a prominent component of the Australian terrestrial biota. However, most squamate (lizard and snake) lineages in Australia appear to be derived from relatively recent dispersal from Asia (< 30 Ma) and in situ diversification, subsequent to the isolation of Australia from other Gondwanan landmasses. We test the hypothesis that the Australian radiation of diplodactyloid geckos (families Carphodactylidae, Diplodactylidae and Pygopodidae), in contrast to other endemic squamate groups, has a Gondwanan origin and comprises multiple lineages that originated before the separation of Australia from Antarctica. Location Australasia. Methods Bayesian (beast ) and penalized likelihood rate smoothing (PLRS) (r 8s ) molecular dating methods and two long nuclear DNA sequences (RAG‐1 and c‐mos) were used to estimate a timeframe for divergence events among 18 genera and 30 species of Australian diplodactyloids. Results At least five lineages of Australian diplodactyloid geckos are estimated to have originated > 34 Ma (pre‐Oligocene) and basal splits among the Australian diplodactyloids occurred c. 70 Ma. However, most extant generic and intergeneric diversity within diplodactyloid lineages appears to post‐date the late Oligocene (< 30 Ma). Main conclusions Basal divergences within the diplodactyloids significantly pre‐date the final break‐up of East Gondwana, indicating that the group is one of the most ancient extant endemic vertebrate radiations east of Wallace’s Line. At least five Australian lineages of diplodactyloid gecko are each as old or older than other well‐dated Australian squamate radiations (e.g. elapid snakes and agamids). The limbless Pygopodidae (morphologically the most aberrant living geckos) appears to have radiated before Australia was occupied by potential ecological analogues. However, in spite of the great age of the diplodactyloid radiation, most extant diversity appears to be of relatively recent origin, a pattern that is shared with other Australian squamate lineages.     

Small‐scale genetic structure and mating patterns in an extensive sessile oak forest (Quercus petraea (Matt.) Liebl.)

Oaks (Quercus) are major components of temperate forest ecosystems in the Northern Hemisphere where they form intermediate or climax communities. Sessile oak (Quercus petraea) forests represent the climax vegetation in eastern Germany and western Poland. Here, sessile oak forms pure stands or occurs intermixed with Scots Pine (Pinus sylvestris). A large body of research is available on gene flow, reproduction dynamics, and genetic structure in fragmented landscapes and mixed populations. At the same time, our knowledge regarding large, contiguous, and monospecific populations is considerably less well developed. Our study is an attempt to further develop our understanding of the reproduction ecology of sessile oak as an ecologically and economically important forest tree by analyzing mating patterns and genetic structure within adult trees and seedlings originating from one or two reproduction events in an extensive, naturally regenerating sessile oak forest. We detected positive spatial genetic structure up to 30 meters between adult trees and up to 40 meters between seedlings. Seed dispersal distances averaged 8.4 meters. Pollen dispersal distances averaged 22.6 meters. In both cases, the largest proportion of the dispersal occurred over short distances. Dispersal over longer distances was more common for pollen but also appeared regularly for seeds. The reproductive success of individual trees was highly skewed. Only 41 percent of all adult trees produced any offspring while the majority did not participate in reproduction. Among those trees that contributed to the analyzed seedling sample, 80 percent contributed 1–3 gametes. Only 20 percent of all parent trees contributed four or more gametes. However, these relatively few most fertile trees contributed 51 percent of all gametes within the seedling sample. Vitality and growth differed significantly between reproducing and nonreproducing adult trees with reproducing trees being more vital and vigorous than nonreproducing individuals. Our study demonstrates that extensive, apparently homogenous oak forests are far from uniform on the genetic level. On the contrary, they form highly complex mosaics of remarkably small local neighborhoods. This counterbalances the levelling effect of long‐distance dispersal and may increase the species’ adaptive potential. Incorporating these dynamics in the management, conservation, and restoration of oak forests can support the conservation of forest genetic diversity and assist those forests in coping with environmental change.     

Characterization of six microsatellite markers in Trillium camschatcense using a dual‐suppression‐polymerase chain reaction technique

Trillium camschatcense is a herbaceous perennial plant distributed in Hokkaido and northern Honshu, Japan. Geographical variations in the breeding system (partial selfing or obligate outcrossing) are reported in the populations of Hokkaido. We isolated six polymorphic microsatellite loci from this species. The number of allele per locus ranged from four to 12, whereas the expected heterozygosities ranged from 0.69 to 0.83. These markers may allow further investigations to reveal the evolutionary and ecological processes of mating system in T. camschatcense.     

The messenger matters: Pollinator functional group influences mating system dynamics

The incredible diversity of plant mating systems has fuelled research in evolutionary biology for over a century. Currently, there is broad concern about the impact of rapidly changing pollinator communities on plant populations. Very few studies, however, examine patterns and mechanisms associated with multiple paternity from cross‐pollen loads. Often, foraging pollinators collect a mixed pollen load that may result in the deposition of pollen from different sires to receptive stigmas. Coincident deposition of self‐ and cross‐pollen leads to interesting mating system dynamics and has been investigated in numerous species. But, mixed pollen loads often consist of a diversity of cross‐pollen and result in multiple sires of seeds within a fruit. In this issue of Molecular Ecology, Rhodes, Fant, and Skogen ( 2017 ) examine how pollinator identity and spatial isolation influence multiple paternity within fruits of a self‐incompatible evening primrose. The authors demonstrate that pollen pool diversity varies between two pollinator types, hawkmoths and diurnal solitary bees. Further, progeny from more isolated plants were less likely to have multiple sires regardless of the pollinator type. Moving forward, studies of mating system dynamics should consider the implications of multiple paternity and move beyond the self‐ and cross‐pollination paradigm. Rhodes et al. ( 2017 ) demonstrate the importance of understanding the roles that functionally diverse pollinators play in mating system dynamics.     

Lectin-Binding Sites Involved in Paramecium primaurelia Mating Pair Formation

ABSTRACT. Mating pair formation in Paramecium primaurelia was shown to be inhibited by incubating mating-competent mating type (mt) I and mt U cells with Limulus polyphemus agglutinin (LPA) or wheat germ agglutinin (WGA). Preincubation of LPA and WGA with their specific binding-monosaccharides, N-acetylneuraminic acid (NeuAc) and N-acetylglucosamine (GlcNAc), respectively, prevented the lectin effect on pair formation. Addition either of NeuAc or GlcNAc resulted in a reversal of cell pairing inhibition by LPA or WGA, respectively. Both NeuAc and GlcNAc monosaccharides inhibited pair formation when their concentration exceeded a threshold value. The pattern of the relative distribution of NeuAc and GlcNAc molecules on the cell surface was analyzed using fluorescence resonance energy transfer techniques combined with imaging systems. Mt I1 cells showed a high lectin-binding site density localized just on the surface region engaged in conjugation. The pattern of mt I cells, consisting of a quite homogeneous lectin-binding site density spread on the cell surface, was also common to nonmating-competent cells and to immature cells. These findings suggest that in P. primaurelia pair formation involves both NeuAc and GlcNAc residues and that the development of mating-competence is related to a modification in NeuAc and GlcNAc relative distribution on the cell surface of mt 11 cells.     

Older than New Caledonia emergence? A molecular phylogenetic study of the eneopterine crickets (Orthoptera: Grylloidea)

Aim A New Caledonian insect group was studied in a world‐wide phylogenetic context to test: (1) whether local or regional island clades are older than 37 Ma, the postulated re‐emergence time of New Caledonia; (2) whether these clades show evidence for local radiations or multiple colonizations; and (3) whether there is evidence for relict taxa with long branches in phylogenetic trees that relate New Caledonian species to geographically distant taxa. Location New Caledonia, south‐west Pacific. Methods We sampled 43 cricket species representing all tribes of the subfamily Eneopterinae and 15 of the 17 described genera, focusing on taxa distributed in the South Pacific and around New Caledonia. One nuclear and three mitochondrial genes were analysed using Bayesian and parsimony methods. Phylogenetic divergence times were estimated using a relaxed clock method and several calibration criteria. Results The analyses indicate that, under the most conservative dating scenario, New Caledonian eneopterines are 5–16 million years old. The largest group in the Pacific region dates to 18–29 Ma. New Caledonia has been colonized in two phases: the first around 10.6 Ma, with the subsequent diversification of the endemic genus Agnotecous, and the second with more recent events around 1–4 Ma. The distribution of the sister group of Agnotecous and the lack of phylogenetic long branches in the genus refute an assumption of major extinction events in this clade and the hypothesis of local relicts. Main conclusions Our phylogenetic studies invalidate a simple scenario of local persistence of this group in New Caledonia since 80 Ma, either by survival on the New Caledonian island since its rift from Australia, or, if one accepts the submergence of New Caledonia, by local island‐hopping among other subaerial islands, now drowned, in the region during periods of New Caledonian submergence.     

Male mating success in an aquatically mating pinniped, the harbour seal (Phoca vitulina), assessed by microsatellite DNA markers

Similar to many other pinniped species, harbour seals ( Phoca vitulina ) mate exclusively at sea. Here we present the first attempt to measure male mating success in an aquatically mating pinniped. Male mating success was estimated by paternity analysis in two cohorts of pups born at Sable Island, Nova Scotia, Canada, using microsatellite DNA markers. The genotypes of 275 pups born in 1994 and 1995 were compared to those of 90 candidate males at six microsatellite loci using a likelihood approach to resolve paternity. Paternity could be assigned for two, 22, 40 and 85 pups at confidence levels of 95, 80, 65 and 50%, respectively. Most successful males were assigned the paternity of a single offspring, suggesting a low variance in male mating success relative to most pinniped species. The proportion of paternal half sibs within cohorts and between maternally related sibs estimated by maximum likelihood were not significantly different from zero. It is thus unlikely that most offspring were sired by a small number of highly successful unsampled males, and that female harbour seals do not usually exhibit fidelity to the same male in sequential breeding seasons. A low level of polygyny in Sable Island harbour seals is consistent with predictions based on their breeding ecology, as females are highly mobile and widely dispersed in the aquatic mating environment at Sable Island.     

Exposure to parasites increases promiscuity in a freshwater snail

Under the Red Queen hypothesis, outcrossing can produce genetically variable progeny, which may be more resistant, on average, to locally adapted parasites. Mating with multiple partners may enhance this resistance by further increasing the genetic variation among offspring. We exposed Potamopyrgus antipodarum to the eggs of a sterilizing, trematode parasite and tested whether this altered mating behaviour. We found that exposure to parasites increased the number of snail mating pairs and the total number of different mating partners for both males and females. Thus, our results suggest that, in host populations under parasite-mediated selection, exposure to infective propagules increases the rate of mating and the number of mates.