Phylogenetic relationships of Hynobius naevius (Amphibia: Caudata) as revealed by mitochondrial 12S and 16S rRNA genes

Using mitochondrial 12S and 16S rRNA sequences, we investigated phylogenetic relationships among populations of the endemic Japanese salamander Hynobius naevius. Monophyly of this species was recovered only in the maximum parsimony tree and was unresolved in maximum likelihood and Bayesian trees. Instead the following four haplotype clades consistently emerged clearly: Clade 1 from northwestern Kyushu, Clade 2 from Chugoku and northeastern Kyushu, Clade 3 from western Shikoku and Kyushu, and Clade 4 from Chubu-Kinki and central-eastern Shikoku. Of these, Clades 1 and 2, and Clades 3 and 4, respectively, correspond to Groups A and B previously recognized from the analyses of allozyme data in this species, but monophyly of these groups was not strongly supported. Unlike the previous results, the western and eastern samples from Shikoku did not form a clade, and were grouped with Kyushu-B in Clade 3 and Chubu-Kinki in Clade 4, respectively. The reason for this conflict between mtDNA and allozyme results is unknown, but might be related to retention of ancestral mtDNA polymorphism in Shikoku populations. Nearly simultaneous divergence of as many as four lineages in wide-ranging H. naevius is inferred for the late Miocene-Pliocene history of this taxon.     

Morphological discrimination of two genetic groups of a Japanese salamander, Hynobius naevius (Amphibia, Caudata)

Hynobius naevius, distributed on western Honshu, Shikoku, and Kyushu Islands of Japan, includes two genetically distinct groups (Groups A and B) that have never been delimited morphologically. Using specimens from the entire species range, we investigated the possibility of distinguishing these groups morphologically. Multivariate analyses of morphometric characters resulted in recognition of two groups that corresponded well to the two genetic groups. One (Group A) was characterized by larger body, compressed tail, shallower vomerine tooth series, bluish- or reddish-purple ground color, and pale-white lateral markings. In contrast, another (Group B) was characterized by smaller body, cylindrical tail, longer vomerine tooth series, reddish-brown ground color, and white lateral markings. Group A was composed of populations from the Chugoku District of Honshu and northern Kyushu, and could not be divided into subgroups, while Group B encompassed populations from the Chubu and Kinki Districts of Honshu, Shikoku and Kyushu, and was subdivided into three local subgroups that are geographically separated by marine straits. Morphometric differentiation in Group A is presumed to have been less affected by genetic factors than by other factors, such as ecological relationships with other, coexisting species. Differentiation in Group B is assumed to have been enhanced not only by genetic but also by climatological factors.     

Phylogenetic Relationships of the Creek Chubs and the Spine-Fins: an Enigmatic Group of North American Cyprinid Fishes (Actinopterygii: Cyprinidae)

Phylogenetic analyses based on the complete nucleotide sequence of the mitochondrial 12S ribosomal RNA gene were performed for representatives of major North American cyprinid clades. These analyses resolved four monophyletic groups: (1) Western Clade, represented by Acrocheilus and Gila , (2) Creek Chub Clade, represented by Couesius, Hemitremia, Semotilus , and Margariscus , (3) Open Posterior Myodome Clade, represented by Campostoma, Phenacobius, Cyprinella, Notropis, Platygobio , and Rhinichthys , and (4) Plagopterin Clade, represented by Snyderichthys, Lepidomeda , and Meda . The overall results of these analyses refute previous hypotheses of relationships of North American Cyprinidae based on morphological data. Our analyses support recognition of Snyderichthys , formerly considered a subgenus of Gila, and indicate that the Plagopterin Clade is sister to the Creek Chub Clade. Furthermore, this analysis indicates that hypotheses of relationship between plagopterins and other Western taxa are unsupported and the Open Posterior Myodome Clade is a monophyletic group.     

Patterns of genetic diversity in the polymorphic ground snake (Sonora semiannulata)

We evaluated the genetic diversity of a snake species with color polymorphism to understand the evolutionary processes that drive genetic structure across a large geographic region. Specifically, we analyzed genetic structure of the highly polymorphic ground snake, Sonora semiannulata, (1) among populations, (2) among color morphs (3) at regional and local spatial scales, using an amplified fragment length polymorphism dataset and multiple population genetic analyses, including F_ST-based and clustering analytical techniques. Based upon these methods, we found that there was moderate to low genetic structure among populations. However, this diversity was not associated with geographic locality at either spatial scale. Similarly, we found no evidence for genetic divergence among color morphs at either spatial scale. These results suggest that despite dramatic color polymorphism, this phenotypic diversity is not a major driver of genetic diversity within or among populations of ground snakes. We suggest that there are two mechanisms that could explain existing genetic diversity in ground snakes: recent range expansion from a genetically diverse founder population and current or recent gene flow among populations. Our findings have further implications for the types of color polymorphism that may generate genetic diversity in snakes.     

Flower color-flower scent associations in polymorphic Hesperis matronalis (Brassicaceae)

Floral scent emission rate and composition of purple and white flower color morphs of Hesperis matronalis (Brassicaceae) were determined for two populations and, for each, at two times of day using dynamic headspace collection and GC-MS. The floral volatile compounds identified for this species fell into two main categories, terpenoids and aromatics. Principal component analysis of 30 compounds demonstrated that both color morphs emitted more scent at dusk than at dawn. Color morphs varied in chemical composition of scent, but this differed between populations. The white morphs exhibited significant differences between populations, while the purple morphs did not. In the white morphs, one population contains color-scent associations that match expectations from classical pollination syndrome theory, where the flowers have aromatic scents, which are expected to maximize night-flying moth pollinator attraction; in the second population, white morphs were strongly associated with terpenoid compounds. The potential impact that pollinators, conserved biosynthetic pathways, and the genetics of small colonizing populations may have in determining population-specific associations between floral color and floral scent are discussed.     

Differential Aggression in Genetically Different Morphs of the White-throated Sparrow (Zonotrichia albicollis)

To see if genetic differences correlate with differences in agonistic behavior, 225 encounters within and between color morphs of the white-throated sparrow (Zonotrichia albicollis) were observed in feeding groups of different sizes and morphic compositions. Tan morphs lack the M chromosome that replaces either of two chromosomes in the white morph. The data were analysed using quantitative models accounting for the proportions of morphs present, and the principal finding was that morphs are equally frequent recipients of aggression but the white morph was the aggressor more frequently than by chance expectation — regardless of the morph of the recipient, the size of the group or the morphic composition of the group.     

Floral color variation and associations with fitness‐related traits in Malva moschata (Malvaceae)

Genetic polymorphisms for floral color are interesting phenomena to study because they are likely to be maintained by opposing selective forces. Pollinator preferences may exert direct selection on floral color; however, floral color might also be the indirect target of selection through genetic associations with other traits under selection. Malva moschata (Malvaceae) is a North American species that produces either red or white flowers. In the present study, we present reflectance spectrophotometry data that characterize the nature of floral color variation in this species and show that honey bees and bumble bees should be able to distinguish between the morphs through differential sensitivity at the green (long‐wavelength) photoreceptor. Second, we use a series of phenotypic measures to investigate whether the color morphs differ with respect to other floral traits, vegetative traits or female reproductive success, and use a series of correlation analyses to infer the relative independence of color from these other traits. We found that red‐flowered morphs produced more anthers per flower and had greater leaf area, and that white‐flowered morphs had greater percentage fruit set; however, there were no reproductive success differences between the morphs. The relationship between flower size and anther number was the only correlation that differed between the morphs. Finally, a series of pollinator‐choice experiments showed that bumble bees strongly prefer red morphs in terms of visit frequency and duration, but honey bees have no preference. Taken together, our results suggest that color is rather independent of other phenotypic traits, and that honey bee abundance is likely to play a role in maintaining color variation in this system.     

Occurrence of two types of Hynobius naevius in Northern Kyushu, Japan (Amphibia: Urodela)

A survey to examine genetic variation among Hynobius naevius from four localities of Fukuoka Pref., northern Kyushu, Japan, resulted in the detection of two, sympatric, genetic types (A and B) that are clearly different in the allelic frequencies of four loci (ACOH-A, ACOH-B, ADH-A, and SOD-A) in each locality. Morphological investigations between the two genetic types also proved that they are clearly discriminated; the type A is about 75 mm in SVL, lacks mottling pattern on bluish purple dorsum, and possesses relatively short vomerine teeth series, while the type B is about 60 mm in SVL, and has light mottling on reddish purple ground color. These results strongly suggest that reproductive isolation occurs between these two types, and that they could be regarded as separate species. Populations from Toyota-cho, western Honshu, and Yabe-machi, central Kyushu, both close to Fukuoka Pref., were very similar to the types A and B, respectively. From these results, we consider that two evolutionary lineages that first evolved allopatrically in western Honshu and southern Kyushu secondarily contacted and became sympatric in the region of northern Kyushu.     

Phylogenetic relationships of the North American chorus frogs (Pseudacris: Hylidae)

We examined phylogenetic relationships of the North American chorus frogs (Pseudacris: Hylidae) from 38 populations using 2.4 kb of 12S and 16S mtDNA to elucidate species relationships and examine congruence of previous phylogenetic hypotheses. Parsimony, maximum likelihood, and Bayesian phylogenies are consistent and reveal four strongly supported clades within Pseudacris: (1). A West Coast Clade containing regilla and cadaverina, (2). a Fat Frog Clade including ornata, streckeri, and illinoensis, (3). a Crucifer Clade consisting of crucifer and ocularis, and (4). a Trilling Frog Clade containing all other Pseudacris. Explicit hypothesis testing using parametric bootstrapping indicates that previous phylogenetic hypotheses are rejected by our sequence dataset. Within the Trilling Frog Clade, brimleyi and brachyphona form the sister group to the Nigrita Clade: nigrita, feriarum, triseriata, kalmi, clarkii, and maculata. The Nigrita Clade shows geographic division into three clades: (1). populations of maculata and triseriata west of the Mississippi River and Canadian populations, (2). southeastern US populations of feriarum and nigrita, and (3). northeastern US populations of feriarum, kalmi, and triseriata. We find that subspecific epithets for crucifer (crucifer and bartramiana) and nigrita (nigrita and verrucosa) are uninformative, therefore we discourage recognition of these subspecies. Pseudacris regilla, cadaverina, ocularis, and crucifer are maintained in Pseudacris.     

Evaluating Genetic Diversity for the Conservation of the Threatened Galapagos Endemic Calandrinia galapagosa (Portulacaceae)

Calandrinia galapagosa (Portulacaceae) is a threatened plant endemic to San Cristobal Island, Galapagos. The species is threatened by goat herbivory: less than 1300 individuals remain in nine populations, three of which have been fenced for protection. It is not known whether these three populations are genetically representative of the species at large or whether the three distinct color morphs exhibited by the species represent different taxonomic units. We measured the frequency of 113 polymorphic amplified fragment length polymorphism markers in 189 specimens representing three different phenotypes from all nine populations to relate the genetic structure of the species to both its geological history and morphological variation. The analysis revealed high diversity within populations and low, but significant, differentiation between populations. In addition, no genetic diversification was observed across color morphs. We conclude that (1) regular gene flow has historically occurred between populations, and (2) individual color morphs are not separate taxa. We identify another population that should be fenced to ensure maximal protection of genetic variation. Our research serves as a case study of using population molecular genetics for optimizing protection strategies for rare plants in tropical archipelagoes affected by introduced herbivores.     

Flower constancy in the hoverflies Episyrphus balteatus (Degeer) and Syrphus ribesii (L.) (Syrphidae)

The causes and consequences of flower constancy have been thefocus of many studies, but almost all have examined the foragingbehavior of bumblebees, honeybees, or butterflies. We test whetherconstancy occurs in an overlooked group of pollinators, thesyrphid flies. Foraging sequences of wild flies of two species,Episyrphus balteatus and Syrphus ribesii were examined whenvisiting flowers in seminatural plant communities and in artificialarrays of two color morphs of Lobularia maritima planted ata range of frequencies. Both species exhibited marked floralconstancy when foraging in the mixed-plant community. Becauseall groups of pollinating insect so far examined exhibit constancyat least under some circumstances, we suggest that this is thepredominant strategy used by pollinators and that there is probablya common explanation. Neither syrphid species exhibited constancyto different color morphs within a plant species, in contrastto previously published studies of Hymenoptera foraging amongpolymorphic flowers, which all describe positive frequency-dependentselection. Possible explanations for this discrepancy are discussed.We argue that constancy in these syrphids is unlikely to resultfrom learning constraints on handling ability, currently themost widely accepted explanation for flower constancy, becausethey forage primarily for pollen which is easily located inmostflowers they visit.     

基于16S rRNA序列的角蟾科部分属间系统关系

采用最大似然法(ML法)、最大简约法(MP法)、邻接法(NJ法)对来自角蟾科Megophryidae(Anura)8属17种及外群2种共25条400bp左右的线粒体16S rRNA序列进行系统发育关系分析。结果表明,用于分析的所有角蟾科物种形成两大支,第一支包括Megophrys,Brachytarsophrys和Atympanophrys,第二支包括Leptobrachium,Leptolalax,Scutiger,Oreolalax和Vibrissaphora。支持将角蟾科划分为两大类群,即第一支属于Megophryini族．第二支属于Leptobrachiini族。根据分子钟模型初步推测两类群问的分歧时间大致为14．2～18．7百万年前。在Megophryini族中,基因树的拓扑结构不支持Atympanophrys建立后的Megophrys为单系;而在Leptobrachiini族中,Leptolalax为一有效属,其系统发生较早。     

FLOWER COLOR POLYMORPHISM AND POLLINATION BIOLOGY OF PLATYSTEMON CALIFORNICUS BENTH. (PAPAVERACEAE)

Five genetically controlled flower color morphs in Platystemon californicus tend to occur in distinct geographic regions, suggesting regional selection of morphs. I examined the reproductive biology of P. californicus to determine whether color morphs are subject to selection due to differences in pollinator attractiveness. Plants of P. californicus have a high pollen: ovule ratio and are highly self-incompatible. Solitary bees (Andrenidae and Halictidae) are the most effective pollen vectors, but show inconsistent discrimination among color morphs. Platystemon californicus is unusual among annual self-incompatible plants in that wind is an important pollen vector. As a result of wind pollination, most polymorphic populations show no intermorph seed-set differences. Therefore, the geographic distribution of flower color morphs cannot be explained by differential attractiveness of color morphs to pollinators in different regions. Any selective value of color morphs must be due to linkage of flower color with as yet undetected morphologically or physiologically adaptive characters.     

The genetic basis of naturally occurring pollen color dimorphisms in Nigella degenii (Ranunculaceae)

Nigella degenii ssp. barbro and ssp. jenny differ from related taxa in being dimorphic for pollen color, with some plants having dark pollen and others light pollen. In this study we performed experimental crosses to determine whether the difference in pollen color is governed by few or many loci and whether the two subspecies utilize the same gene to control pollen color. Patterns of segregation in crosses between morphs show that dark pollen is dominant over light pollen and that a single major gene is responsible for most of the variation in pollen color. Consequently it should be relatively easy for pollen color dimorphisms to establish and spread in these subspecies. Aberrant segregation ratios were attributed to genetic factors that reduced the expression of the allele conferring dark pollen or processes that sorted between color morphs during seed development. Crosses between dark pollen plants from different subspecies showed signs of complementation in the F2 generation, but the frequency of the light morph was too low to support a model involving complementary action of recessive alleles at two separate loci. Based on this and other observations, we hypothesize that the pollen color difference is controlled by the same major locus in the two subspecies.     

Differences in Mating Propensity Between Immature Female Color Morphs in the Damselfly Ischnura elegans (Insecta: Odonata)

Female-limited color polymorphisms occur in a variety of animal taxa where excessive male sexual harassment may explain the coexistence of multiple female color morphs. In the color polymorphic damselfly Ischnura elegans, mature and immature female color morphs coexist at the mating site where males are in search for suitable mating partners. Here, we study male preference and female mating propensity for the two immature female morphs. As would be expected, compared to mature morphs, both immature female morphs mate much less. Within immature females, one morph consistently mates more frequently compared to the other morph, a pattern that is similar for the ontogenetically corresponding mature female morphs. Preference experiments with the two differently colored immature female morphs, however, did not indicate male mate preference for either morph. Low mating frequencies of immature females at natural sites in combination with relatively high attractiveness of immature models in terms of male preference indicate that female behavior influences female mating success.     

不同大豆品种上红绿两种色型豌豆蚜的种群参数

【目的】探讨不同大豆品种对红绿两种色型豌豆蚜Acyrthosiphon pisum种群参数的影响,为大豆品种的抗蚜性评价及豌豆蚜的预测预报与综合防治提供试验依据。【方法】在光周期10L∶14D、温度23±1℃,相对湿度60%±10%,光照强度212μmol/m~2·s的人工气候箱中,观察和分析4个大豆品种(汾豆牧绿2号、南夏豆25、南黑豆20和南豆5号)叶片上红绿两种色型豌豆蚜的成虫寿命、繁殖和种群生命表参数。【结果】在大豆品种汾豆牧绿2号上,红绿两种色型豌豆蚜成虫寿命均最短,繁殖力均最弱,且红色型豌豆蚜成虫寿命比绿色型长1.07 d,内禀增长率是绿色型豌豆蚜的29.93倍;在南夏豆25上,红色型豌豆蚜成虫寿命比绿色型长2.46 d,内禀增长率是绿色型豌豆蚜的5.86倍;在南黑豆20上,红色型豌豆蚜成虫寿命比绿色型长2.47 d,内禀增长率是绿色型豌豆蚜的1.54倍;在南豆5号上,红色型豌豆蚜成虫寿命比绿色型短0.02 d,内禀增长率是绿色型豌豆蚜的1.41倍。【结论】不同大豆品种对红色和绿色型豌豆蚜种群参数的影响不同,且两种色型豌豆蚜对不同大豆品种适应性反应也不相同。     

Host nest defense against a color-dimorphic brood parasite: great reed warblers (Acrocephalus arundinaceus) versus common cuckoos (Cuculus canorus)

We tested great reed warbler (Acrocephalus arundinaceus) discrimination against two common cuckoo (Cuculus canorus) female color morphs (gray and rufous) in two areas with different parasitism rates and proportions of the two morphs. Hosts recognized the two cuckoo morphs from a control, the feral pigeon (Columba livia), at Apaj, Hungary (where brood parasitism was heavy), whereas no significant differences among the models were recorded at Lužice, Czech Republic (where the parasitism rate was moderate). At Apaj, the hosts discriminated the rufous morph (which is slightly predominant there) better than the gray morph from the control. Between-site comparison (after controlling for background aggression) revealed that great reed warblers were more aggressive towards the rufous morph at Apaj than at Lužice, whereas their responses to the gray morph did not differ, corresponding with much higher between-site difference in the relative abundance of the rufous morph. Our results suggest that both local parasitism pressure and relative abundance of two female color morphs of a brood parasite may significantly influence host nest defenses.     

Aggression and fitness differences between plumage morphs in the common buzzard (Buteo buteo)

Genetic plumage polymorphism in birds is increasingly recognizedas a potentially important trait influencing birds’ lifehistories. In the common buzzard Buteo buteo, the 3 color morphsvary in lifetime reproductive success (LRS), but the proximatemechanisms leading to these differences are unknown. We firstconfirmed the stability of the fitness differences found previously,using a greatly extended LRS data set. To find potential causesfor these differences, we experimentally studied variation inaggressive behavior of the morphs, both against an interspecificpredator and intraspecific competitors. The morphs showed substantialvariation in aggressive behavior. Light-colored males were mostaggressive toward an interspecific predator, followed by intermediateand dark males. In females, this pattern was reversed, resultingin sex-related differences of aggression in 2 morphs. When defendingtheir territory against intraspecific competitors, no absolutedifference in aggression was found, but the morphs reacted strongesttoward intruders of a morph similar to their own. This suggeststhat aggression differs both between and within morphs, leadingto a complex pattern on the population level. Coupled with thestrong fitness differences, our results suggest that the geneticbasis of the polymorphism has far-reaching behavioral consequences.