Ecological subspecies and locally temporal populations of anadromous fish

Intraspecific organization and structure of anadromous fish populations (in terms of species of the Oncorhynchus, Salvelinus, and Tribolodon genuses) were investigated. It was shown that the ecological, genetic, and morpho-physiological differences in ecology-temporal (seasonal) races of these fish reached the rank of ecological subspecies. The expediency of more careful and detailed study of intraspecific organization, ecological and locally temporal differentiation of fish, and consideration of the results of these researches was shown in the development of a polymorphic species concept as well as optimization of fish industry—the sustainable organization of fishing, artificial fish breeding, and introduction of fish.     

Ecomorphology of a generalist freshwater gastropod: complex relations of shell morphology,habitat, and fecundity

Evolutionary and ecological situations in a species’ native and invasive ranges can be drastically different. This is the case for Potamopyrgus antipodarum Gray (1843) a morphologically highly variable freshwater snail native to New Zealand, where sexual and asexual individuals coexist and experience selective pressure by sterilizing endoparasites. By contrast, only a few asexual lineages have been established in invaded regions around the globe, where parasite infection is extremely rare. We analyzed the ecomorphology of 996 native P. antipodarum in a geometric morphometric framework, using brood size as proxy for fecundity, and mtDNA and nuclear SNPs to account for relatedness and identify reproductive mode. As expected, we found genetic and morphological diversity to be higher in native than in invasive snails investigated previously, but surprisingly no higher morphological diversity in sexual versus asexual individuals. The relationships between shell morphology, habitat, and fecundity were complex. Shape variation was primarily linked to genetic relatedness but specific environmental factors including flow rate induced similar shell shapes. By contrast, shell size was largely explained by environmental factors. Fecundity was correlated with size but showed trade-offs with shape in increasingly extreme conditions. With increasing flow and toward small springs, the trend of shell shape becoming wider was reversed, i.e., snails with narrower shells were brooding more embryos. We concluded that both genetic and environmental contributions to variation in shell morphology in P. antipodarum likely play an important role in the ability of this species to adapt to a wide spectrum of habitats.     

The <Emphasis Type="Italic">Cotesia sesamiae</Emphasis> story: insight into host-range evolution in a Hymenoptera parasitoid and implication for its use in biological control programs

This review covers nearly 20 years of studies on the ecology, physiology and genetics of the Hymenoptera Cotesia sesamiae, an African parasitoid of Lepidoptera that reduces populations of common maize borers in East and South Africa. The first part of the review presents studies based on sampling of C. sesamiae from maize crops in Kenya. From this agrosystem including one host plant and three main host borer species, studies revealed two genetically differentiated populations of C. sesamiae species adapted to their local host community, and showed that their differentiation involved the joint evolution of virulence genes and sensory mechanisms of host acceptance, reinforced by reproductive incompatibility due to Wolbachia infection status and natural inbreeding. In the second part, we consider the larger ecosystem of wild Poales plant species hosting many Lepidoptera stem borer species that are potential hosts for C. sesamiae. The hypothesis of other host-adapted C. sesamiae populations was investigated based on a large sampling of stem borer larvae on various Poales across sub-Saharan Africa. The sampling provided information on the respective contribution of local hosts, biogeography and Wolbachia in the genetic structure of C. sesamiae populations. Molecular evolution analyses highlighted that several bracovirus genes were under positive selection, some of them being under different selection pressure in C. sesamiae populations adapted to different hosts. This suggests that C. sesamiae host races result from co-evolution acting at the local scale on different bracovirus genes. The third part considers the mechanisms driving specialization. C. sesamiae host races are more or less host-specialized. This character is crucial for efficient and environmentally-safe use of natural enemies for biological control of pests. One method to get an insight in the evolutionary stability of host-parasite associations is to characterize the phylogenetic relationships between the so-called host-races. Based on the construction of a phylogeny of C. sesamiae samples from various host- and plant species, we revealed three main lineages. Mechanisms of differentiation are discussed with regard to the geography and ecology of the samples. One of the lineage presented all the hallmarks of a distinct species, which has been morphologically described and is now studied in the perspective of being used as biological control agent against Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae), a major maize pest in West Africa and Mediterranean countries (see Benoist et al. 2017). The fourth part reviews past and present use of C. sesamiae in biological control, and points out the interest of such molecular ecology studies to reconcile biodiversity and food security stakes in future biological control.     

Size-selective predation by all-male prawns: implications for sustainable biocontrol of snail invasions

All-male populations of the freshwater prawn Macrobrachium rosenbergii were recently produced by a novel temporal RNA interference (RNAi)-based biotechnology for aquaculture purposes. This biotechnology opens the way to the wide use of all-male prawn populations as sustainable biocontrol agents against invading populations of freshwater snails, for which there is currently no environmentally friendly solution. Among the most damaging of the invasive freshwater snail species are the apple snails (Pomacea spp.), which inflict major damage on natural ecosystems and rice fields. The proposed use of all-male prawn populations as environmentally friendly biocontrol agents against invasive freshwater snails has several advantages: efficient predation by the prawns over a wide range of freshwater snails, the ready availability of the prawns, and the monosex non-reproductive nature of the biocontrol agents. Since the aquatic predators are strongly size selective, we quantified the predation rate as a function of body size of both predator and prey (M. rosenbergii and P. caniculata). Medium-sized and large prawns (~10–30 g) efficiently preyed small and medium-sized snails (up to 15 mm), while small prawns (up to 4 g) immediately and completely eradicated snail hatchlings. Medium-sized prawns (~22 g) exterminated a significant fraction of snail biomass within 24 h (up to 58% of their body mass) after being introduced into a tank of snails. A typical ‘climbing-to-the surface’ anti-predator behavior of the snails was recorded. The potential of all-male prawns as efficient biocontrol agents over hatchling and adult apple snails as part of an integrated pest management program is discussed. Our experiments set the stage for evaluating the ecological and economic implications of this generic solution for a wide variety of habitats.     

Feeding behavior,ration and size structure of a population of the predatory gastropod <Emphasis Type="Italic">Cryptonatica janthostoma</Emphasis> in Vostok Bay,Sea of Japan

The relationships between the shell height of the predatory gastropod Cryptonatica janthostoma and the shell length of its typical prey, the bivalve Ruditapes philippinarum, and the diameter of the borehole on the prey shell resulting from a successful attack of the predator were experimentally found and assessed statistically. The shell height of C. janthostoma calculated retrospectively from the borehole diameter using the obtained relationships was 17–52 mm. The prey of C. janthostoma are burrowing bivalves, whose populations are affected by the predator to a varying degree. In populations of medium-sized mollusks (R. philippinarum, Protothaca euglypta, P. jedoensis, and others), C. janthostoma feeds on mollusks larger than 7–10 mm; in species with a shell length greater than 100 mm (Callista brevisiphonata, Saxidomus purpuratus), it eats specimens of 10–58 mm. C. janthostoma apparently has no effect on populations of small-sized mollusks (Anisocorbula venusta) and mollusks with an active avoidance response (Clinocardium californiense).     

<Emphasis Type="Italic">Westiellopsis ramosa</Emphasis> sp. nov., intensely branched species of <Emphasis Type="Italic">Westiellopsis</Emphasis> (cyanobacteria) from a freshwater habitat of Jabalpur,Madhya Pradesh,India

An axenic culture of a cyanobacterium (strain HPS) was raised from a field specimen of greenish planktonic floccose mass from a local lake, Ganga Sagar. Intense morphological examination and comparative morphological assessment with the genera Fischerella and Hapalosiphon and all the known strains of the genus Westiellopsis indicated that the strain HPS differed in morphology with the closely related strains in trichome arrangement, size of vegetative cells, heterocytes, monocytes, and number of rows of main filaments. There were also differences in the habitat preference, being aquatic rather than terrestrial or subaerial. Intense ecological characterization of the habitat was performed through measurements of important physicochemical characteristics. 16S rRNA gene-based identification and phylogenetic placement indicated conclusively that the strain HPS was different from the most closely related strain Westiellopsis prolifica SAG 16.93. Phylogenetic inferences drawn in between all the branched heterocytous forms and subsequent 16S-23S ITS analyses and folding of the secondary structures revealed an entirely new form that is unknown till now. Subsequent nifD and rbcL gene-based phylogenetic assessments indicated that strain HPS is phylogenetically different from all the other previously known species of true branching cyanobacteria, along with also pointing toward the huge database inconsistencies in case of true branched cyanobacteria. Assessment of morphological and ecological differences along with comprehensive phylogenetic evaluation indicated that the strain HPS is a new species of the genus Westiellopsis and the name being proposed is Westiellopsis ramosa sp. nov.     

Distribution and quantitative characteristics of common species of pond snails of the subgenera <Emphasis Type="Italic">Peregriana</Emphasis> and <Emphasis Type="Italic">Radix</Emphasis> (Mollusca: Gastropoda: Lymnaeidae) in waterbodies of the south of Western Siberia

Information on some ecological features of eight species of pond snails belonging to the subgenera Peregriana and Radix (Lymnaea ampla (Hartmann), L. ampullacea (Rossmässler), L. auricularia (L.), L. balthica (L.), L. fontinalis (Studer), L. lagotis (Schrank), L. ovata (Draparnaud), and L. tumida (Held)) in the waterbodies of south of Western Siberia is presented. The patterns of the species distribution and their cooccurrence in different waterbodies have been studied. An analysis of the quantitative variables (abundance and biomass) of the snails in the waterbodies of the Karasuk lake-river system and in the Novosibirsk Reservoir has been performed.     

Unisexual reproduction: Either maternal or paternal inheritance

Parthenogenesis is usually recognized as the most accepted mechanism of cloning, i.e., reproduction without genetic recombination. Transfer from bisexual to parthenogenetic propagation causes the appearance of all-female populations, races, and species. It was ascertained in natural populations of numerous of reptile and insect species. Clonal and hemiclonal species of fishes and amphibians propagate by means of gynogenesis and hybridogenesis. Less known are instances of androgenesis found in some insects and mollusks. In this case offspring develops only under control of male genes supplied by spermatozoa. Mother’s genes included into the egg nucleus have to be entirely lost. Androgenesis may be called mirroring of parthenogenesis.     

Life history traits determine the differential vulnerability of native and invasive apple snails (<Emphasis Type="Italic">Pomacea</Emphasis> spp.) to a shared juvenile-stage predator

The vulnerability of gastropods to their predators varies with life history traits such as morphology, body size, behavior, and growth rates as well as predator size. A recent study suggested that the invasive apple snail, Pomacea maculata, was considerably more vulnerable to crayfish predators than the native Florida apple snail, P. paludosa. The difference was hypothesized to be caused by the relatively small hatchling size of P. maculata. To test this hypothesis, we conducted a series of feeding assays designed to quantify maximum feeding rates and selective foraging of crayfish on apple snails. The rate at which crayfish killed individual P. maculata (i.e., kill rates) decreased with snail size, and kill rates on both species increased with crayfish size. Kill rates on juvenile P. maculata were higher than kill rates on size-matched hatchling P. paludosa, and crayfish fed selectively on P. maculata when offered mixed groups of size-matched snails. Further analyses revealed that hatchling P. paludosa possess shells 1.8× heavier than size-matched P. maculata suggesting differences in vulnerability to crayfish were consistent with interspecific differences in shell defenses. Differences in hatchling size and defensive traits in combination make crayfish kill rates on hatchling P. maculata approximately 15.4× faster than on hatchling P. paludosa, but the relative contribution of hatchling size to differences in apple snail vulnerability was >3× greater than the contribution of defensive traits.     

Different ecological conditions support individual specialization in closely related,ecologically similar species

Individual generalist predators often have more specialized diets than their populations do. Individual specialization (IS) is influenced by ecological opportunity, intraspecific competition, and interspecific competition, although the effects of these parameters are inconsistent across studies. We investigated IS in five species of frogs and toads, Anaxyrus americanus, A. fowleri, Lithobates catesbeianus, L. clamitans, and L. sphenocephalus. We used the natural history and ecology of each species to predict which parameters would influence IS. Our predictions were supported for some species but not others. We predicted IS would be positively influenced by resource diversity in all species, but this prediction held for only three species, with the relationship significant in A. fowleri and L. catesbeianus and marginally significant in A. americanus. We also predicted that interspecific competition would have a negative relationship with IS in L. clamitans because L. catesbeianus is competitively superior to L. clamitans and likely to suppress its foraging options. This prediction was upheld. Finally, we predicted that IS in A. americanus, A. fowleri, and L. clamitans would be influenced by intraspecific competition. However, IS was not influenced by intraspecific competition in any species, a surprising result given that intraspecific competition has traditionally been assumed to be the ecological parameter with the strongest effects on IS. Many previous studies did not simultaneously consider all three ecological parameters, which may have increased the apparent importance of intraspecific competition for IS. Our results revealed that the ecological parameters affected IS differently even across closely related and ecologically similar species, and demonstrated that these differences are sometimes predictable based on natural history. This study also suggests that sympatric ecological speciation based on IS may be rare because the ecological parameters driving IS are inconsistent across species, and the strength of their effects on intraspecific diet variation varies in space.     

Ecological ranges and types of rarity in the Kuznetsk Alatau of some <Emphasis Type="Italic">Saussurea</Emphasis> DC. species

An analysis of indicator values of four Saussurea DC. species, S. baicalensis (Adams) B. L. Rob., S. frolowii Ledeb., S. salicifolia (L.) DC., and S. schanginiana (Wydl.) Fisch. ex Serg., have been carried out by the method of indicator scales of soil moisture and nutrient availability and salinity in more than 1600 relevés. The size of their ecological ranges and the values of their competitiveness in phytocenoses are determined. As a result of a comparison of the locality of local populations within the ecological range and their occurrence, the vulnerability of S. baicalensis, S. frolowii, S. salicifolia, and S. schanginiana in the Kuznetsk Alatau is evaluated. The types of rarity for these species in the Kuznetsk Alatau are determined.     

Size structures and comparative phenology of syntopic populations of <Emphasis Type="Italic">Hirudo verbana</Emphasis> and <Emphasis Type="Italic">Hirudo medicinalis</Emphasis> in eastern Ukraine

Ranges of different species of medicinal leeches (Hirudo spp.) are nearly mutually exclusive with very few areas of overlapping. This biogeographical pattern suggests different ecological requirements for the two species. However, two habitats in Hungary and Ukraine where populations of H. verbana and H. medicinalis coexist were found. The aim of this research was to reveal differences in size structures and phenologies between the two species in a steppe pond with two populations. The study was conducted from March to September in 2009 and 2010 in Horila Dolyna, Kharkiv Region. Leeches were collected several times during the season, weighed and released. The abundance of H. verbana was always higher. The Mann-Whitney U-test and the Wilcoxon test were applied. Significant differences between sequential samples within the species were found. The large weight classes of H. verbana emerged by the end of summer and caused a higher variance in contrast to H. medicinalis. This suggests the higher growth rate and the more r-strategic biology of H. verbana in comparison with the largely K-strategic H. medicinalis.     

Do environmental factors affect the male frequency of exotic mangrove species <Emphasis Type="Italic">Laguncularia racemosa</Emphasis> (Combretaceae) along the southeast coast of China?

The exotic mangrove species Laguncularia racemosa (Combretaceae) is fast-growing and was used for forestation in recent years along the southeast coast of China. The breeding system of L. racemosa is variable among populations, such as hermaphroditism, gynodioecy, and androdioecy. To determine whether androdioecy is widespread in L. racemosa, 19 planted populations were surveyed along the southeast coast of China. To determine whether local environmental factors could affect the sex ratio in androdioecious populations, the observed male frequency of different populations was compared to local average annual temperature, rainfall, and salinity. The results showed that the 19 L. racemosa populations along the southeast coast of China were androdioecious. The male frequencies of these populations varied from 31.0 to ?88.9%. Partial correlation analysis showed that average annual salinity explained 74.7% of the male frequency (p?=?0.001). It is reasonable to note that the male frequency followed a general trend, presenting peak that coincided with the low salinity. The average annual rainfall explained only 30.4% of the male frequency (p?=?0.403). And the average annual temperature explained only 20.2% of the male frequency (p?=?0.206). The variable male frequency in different androdioecious L. racemosa populations may presumably be caused by ecological or genetical processes; these hypotheses will be tested in future studies.     

Genetic variation and differentiation in populations of Japanese emperor oak <Emphasis Type="Italic">Quercus dentata</Emphasis> Thunb. and Mongolian oak <Emphasis Type="Italic">Quercus mongolica</Emphasis> Fisch. ex Ledeb.) in the south of the Russian Far East

Allozyme variation of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Ledeb.) was examined in 11 populations of these species from southern Primorye. Analysis of 18 loci showed that in these populations, 66.7% of genes of Mongolian oak are polymorphic, the number of alleles per locus being 2.28. In Japanese emperor oak, these parameters were respectively 59.8 and 2.36%. The observed heterozygosity in both species did not differ from the expected values, constituting 0.198 in Japanese emperor oak and 0.161 in Mongolian oak. The Nei’s distance between Quercus mongolica and Q. dentata was 0.053. The main contribution to the species differentiation is made by loci Lap-1, Idh-1, Pgm-1, and Ndh-1, although none of them is diagnostic. The Japanese emperor oak and Mongolian oak populations formed separate clusters in an UPGMA dendrogram. Taking into account morphological and ecological isolation of the species, we suggest that the differences in gene frequencies may reflect selection acting in favor of adaptation to different growth conditions and counteracting between-species hybridization.     

Challenges in the delimitation of morphologically similar species: a case study of <Emphasis Type="Italic">Tuber brumale</Emphasis> agg. (Ascomycota,Pezizales)

Tuber brumale (winter truffle) is one of the most controversial true truffles, not only in regard to its ecological and economical role but also its taxonomy. Multilocus phylogenetic analyses have revealed that specimens identified earlier as T. brumale belong to two species. These species were deemed cryptic right away, because preliminary morphological measurements did not show any phenotypical differences. In this study, we measured the morphology of 119 T. brumale agg. specimens, identified by DNA-based phylogenetic tools. We found several continuous morphological characters which show strong statistical differences between the two species, albeit not without overlap. Using a combination of these characters, we show that efficient separation of the two species is possible. We describe T. cryptobrumale sp. nov. and present the environmental demands and the potential area reconstruction of both species. We argue that non-representative sampling is a major culprit in most failures to detect both the existence of morphologically similar species and their morphological differences. Our findings illustrate the benefits of integrative taxonomy: the use of a combination of molecular, morphological and ecological tools.     

Local Knowledge on the Uses,Habitat, and Change in Abundance of Multipurpose <Emphasis Type="Italic">Mimusops</Emphasis> Species in Benin

Multipurpose NTFP species typically experience higher harvest demand because of their multiple uses, which, when combined with unsustainable land use practices, may threaten population viability. We assessed local knowledge on the uses, habitat, and population status of Mimusops andongensis and Mimusops kummel, both multipurpose NTFP species in Benin, to promote their valorization and conservation and thus sustain local knowledge on their uses for domestication issues. One hundred households were randomly selected for structured interviews for M. andongensis and 500 for M. kummel. The relationship between age, sex, and ethnic groups and the species uses was assessed using comparison and correspondence analyses. Nearly all organs of the species were used. Both species were mainly exploited for medicinal purposes but also in construction and as firewood. We found similarities in some uses of the species organs, although the species occur in different ecological zones and are used by different ethnic groups. This result should be considered for the valorization of the species. Most informants reported that populations of M. andongensis were decreasing, although some felt that they were increasing, whereas less than one-third said that M. kummel was decreasing. There were strong relationships between gender, age, and ethnic affiliation of the users and the exploited organs of both species. Potential uses exist based on both the past and current uses of the species and in comparison to other countries where they are exploited. Local ethnoecological knowledge and practices will help to valorize and conserve the species. However, further research on the species’ seed germination and propagation ability are also necessary.     

Unraveling cryptic invasion of a freshwater snail in Chile based on molecular and morphological data

Cryptic species may cause biological invasions to be overlooked leading to underestimation of the potential impacts of invaders on the new ecosystems. Identification of freshwater snails is challenging because of the scarcity of discriminative morphological characters and the limited taxonomic knowledge of some taxa. Here, molecular and morphological analyses were performed to investigate the identity of viable populations of the genus Physa in aquatic ecosystems of different basins in northern and central Chile, including habitats where the native species Physa chilensis and Physa nodulosa have been traditionally recognized. Molecular analyses based on mitochondrial DNA sequences from the small subunit 16S rDNA and cytochrome c oxidase subunit 1 identified all specimens sequenced as belonging to the globally invasive species Physa acuta. Microscopic examination of the radula and morphological observations of the reproductive system were congruent with these findings. Highly divergent haplotypes found in El Salto suggest multiple introductions of different lineages of the invader in this locality. It is clear that for future management planning a more reliable assessment of the status of P. chilensis and P. nodulosa is required.     

Geographic variation and temporal population differentiation of chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> from some regions of the Russian Far East

Allozyme variation of chum salmon Oncorhynchus keta was examined in the populations from nine rivers of the Russian Far East. A total of 12 loci were tested, and eight of these were shown to be polymorphic. The greatest contribution to the samples differentiation was made by the EST-D1* and sIDHP-2* loci. Most of the allele diversity was distributed among the individuals within the samples. The among-sample differences within races were statistically significant and accounted for slightly more than 7% of total variation. The differences between the races constituted 0.1% and were statistically nonsignificant. Genetic similarity of seasonal races within single locality allowed suggestion on their secondary formation after settling of founder population into a certain region.     

Comparison of weight-length relationships and relative growth between intertidal and offshore populations of <Emphasis Type="Italic">Hexaplex trunculus</Emphasis> (Gastropoda: Muricidae) from the Gulf of Gabès (southern Tunisia)

The present study reports weight-length (W-L) relationships and discusses the relative growth of the banded murex (Hexaplex trunculus) from intertidal and offshore areas of the Gulf of Gabès (southern Tunisia). Overall, 9634 H. trunculus were sampled (6608 from intertidal and 3026 from offshore), with both populations comprising broad ranges in shell length (intertidal: 13.6–78.5 mm; offshore: 22.9–91.1 mm) and total weight (intertidal: 0.2–63.8 g; offshore: 0.6–92.5 g). In both populations, W-L relationships were highly significant and the morphometric parameters were highly correlated (intertidal: r?=?0.967; offshore: r?=?0.973). Relative growth was significantly different between populations, with intertidal H. trunculus displaying a negative allometry (b?=?2.962) and offshore H. trunculus exhibiting isometric growth (b?=?3.013). Factors influencing total weight (soft-body weight and shell weight) and potentially responsible for differences in W-L relationships and relative growth between populations were discussed. In addition, a useful comparative analysis for fisheries biology, assessment and management purposes was performed with analogous information from other populations of H. trunculus from the Mediterranean Sea and the Atlantic Ocean.     

Feeding choice and predation pressure of two invasive gammarids, <Emphasis Type="Italic">Gammarus tigrinus</Emphasis> and <Emphasis Type="Italic">Dikerogammarus villosus</Emphasis>, under increasing temperature

In most European freshwater ecosystems, the invasive gammarids Gammarus tigrinus and Dikerogammarus villosus strongly impair recipient communities through predation of a wide range of native invertebrates. Due to the effects of temperature on both the physiology and the behaviour of such ectotherms, understanding how global warming may influence their ecological impact is a research priority. These species were therefore exposed to three different food types to determine their detritivorous, herbivorous and carnivorous characters, and predation was measured characterizing the Holling’s functional response. The effect of increasing water temperatures (15, 20, 25°C) on both the food choice and predatory activities was investigated. Both species showed a significant preference for animal tissues at all temperatures. The total food intake increased with temperature for G. tigrinus but did not change for D. villosus, which may result from specific species differences in metabolic requirements. The consumption of live prey strongly increased with temperature. The main differences were an increased searching efficiency in G. tigrinus and a decreased handling time in D. villosus as temperature increased, which may result from differences in foraging strategies. These results suggest that climate change is likely to increase the predation pressure of both invasive gammarids on prey species.