Subspecific Populations Research Articles

Genomic variation in the Black-throated Green Warbler (Setophaga virens) suggests divergence in a disjunct Atlantic Coastal Plain population (S. v. waynei)

AbstractWe used whole-genome resequencing to estimate genetic distinctiveness in the Black-throated Green Warbler (Setophaga virens)—including S. v. waynei—a putative subspecies that occupies a narrow disjunct breeding range along the Atlantic Coastal Plain. Despite detecting low-global differentiation (FST = 0.027) across the entire species, the principal components analysis of genome-wide differences shows the main axis of variation separates S. v. waynei from all other S. v. virens samples. We also estimated a low-migration rate for S. v. waynei, but found them to be most similar to another disjunct population from the Piedmont of North Carolina, and detected evidence of a historical north-to-south geographic dispersal among the entire species. New World wood warblers (family: Parulidae) can exhibit strong phenotypic differences among species, particularly, in song and plumage; however, within-species variation in these warblers—often designated as subspecies—is much more subtle. The existence of several isolated Black-throated Green Warbler populations across its eastern North American breeding range offers an excellent opportunity to further understand the origin, maintenance, and conservation status of subspecific populations. Our results, combined with previously documented ecological and morphological distinctiveness, support that S. v. waynei be considered a distinct and recognized subspecies worthy of targeted conservation efforts.

Historical explanation of genetic variation in the Mediterranean horseshoe bat Rhinolophus euryale (Chiroptera: Rhinolophidae) inferred from mitochondrial cytochrome-b and D-loop genes in Iran

Molecular phylogeography and species distribution modelling (SDM) suggest that late Quaternary glacial cycles have portrayed a significant role in structuring current population genetic structure and diversity. Based on phylogenetic relationships using Bayesian inference and maximum likelihood of 535 bp mtDNA (D-loop) and 745 bp mtDNA (Cytb) in 62 individuals of the Mediterranean Horseshoe Bat, Rhinolophus euryale, from 13 different localities in Iran we identified two subspecific populations with differing population genetic structure distributed in southern Zagros Mts. and northern Elburz Mts. Analysis of molecular variance (AMOVA) obtained from D-loop sequences indicates that 21.18% of sequence variation is distributed among populations and 10.84% within them. Moreover, a degree of genetic subdivision, mainly attributable to the existence of significant variance among the two regions is shown (θCT = 0.68, p = .005). The positive and significant correlation between geographic and genetic distances (R 2 = 0.28, r = 0.529, p = .000) is obtained following controlling for environmental distance. Spatial distribution of haplotypes indicates that marginal population of the species in southern part of the species range have occupied this section as a glacial refugia. However, this genetic variation, in conjunction with results of the SDM shows a massive postglacial range expansion for R. euryale towards higher latitudes in Iran.

The importance of cryptic species and subspecific populations in classic biological control of weeds: a North American perspective

Classical biological control of weeds depends on finding agents that are highly host-specific. This requires not only correctly understanding the identity of the target plant, sometimes to subspecific levels, in order to find suitable agents, but also identifying agents that are sufficiently specific to be safe and effective. Behavioral experiments and molecular genetic tools have revealed that some arthropod species previously thought to be polyphagous really consist of multiple cryptic species, host races or biotypes, some of which are more host-specific than others. Whereas true species are reproductively isolated, individuals from subspecific populations may potentially interbreed with those of other populations if they should encounter them. Furthermore, biotypes may consist of individuals sharing a genotype that is not fixed within a monophyletic group, and thus may not be evolutionarily stable. This raises the question of how such populations should be classified, and how to confirm the identity of live arthropods before releasing them as classical biological control agents. The existence of host races or cryptic species may greatly increase the number of prospective biological control agents available. However, it may also create new challenges for governmental regulation. These issues are discussed using pertinent examples, mainly from North America.

Taxonomic Evaluation of the Greater Horseshoe Bat Rhinolophus ferrumequinum (Chiroptera: Rhinolophidae) in Iran Inferred from the Mitochondrial D-Loop Gene.

To examine the level of genetic differentiation in the sequences of the mitochondrial D-loop gene of Rhinolophus ferrumequinum, and to evaluate the current taxonomic status of this species, 50 tissue samples of greater horseshoe bats were collected in 2011-2015 from 21 different localities in northwest, northeast, west, central, and south regions of Iran. Twenty-two published D-loop sequences from Europe (Switzerland, United Kingdom, Bulgaria, and Tunisia), and Anatolia (south, west, and east Turkey) were downloaded from GenBank. Molecular genetic analyses revealed remarkable variation among populations of R. ferrumequinum. Two major clades with strong support were identified within the greater horseshoe bat. One of these clades consists of individuals of R. ferrumequinum from Iran and eastern Turkey, and is further subdivided into two subclades. A second clade includes samples from western Turkey and Europe. The two subclades from Iran and Turkey and the second clade from western Turkey and Europe represent three diagnosable categories, which most probably warrant three subspecies for the species. Thus, based on genetic differences, it is clear that two subspecific populations are found in Iran: R. f. irani (southern Iran) and R. f. proximus (northern Iran).

Morphometric evaluation of the two mink subspecies in Illinois

The 2 subspecies of mink (Neovison vison letifera and N. v. mink) in Illinois were characterized early in the 20th century; however, quantifiable morphological distinctions between the 2 subspecies remain unclear. Illinois biogeography, and the influence of glaciations on animal populations, might explain the distinctions between the 2 mink subspecies. We evaluated sexual dimorphism within each subspecies and morphologic variation between subspecific populations. Oral, facial, and braincase regions were defined by 22 dimensions. Sexual dimorphism was present in both subspecies of mink. Data were adjusted for sex differences and tested for differences between subspecies using analysis of variance and multivariate analysis of variance. Cranial dimensions differed significantly between N. v. letifera and N. v. mink. Cranial dimensions distinguish individuals of the 2 geographically distinct subspecies; however, an intergradation zone might be present. The results are consistent with population response to glaciations and subsequent expansion, however, further genetic testing is necessary to test this historical biogeography of N. vison.

Morphological variation in Acrossocheilus hemispinus (Teleostei: Cyprinidae: Barbinae), with comments on its taxonomic status

Differences in coloration and morphology between two subspecies of Acrossocheilus hemispinus were investigated based on museum-stored and freshly-caught specimens. There are marked differences in the coloration of either juveniles or adults, and in sexual dimorphism, between A. h. hemispinus and A. h. cinctus. Multivariate analysis of morphometric data too, shows the two taxa to be distinguishable from each other. Differences in body coloration and morphometric characters coincide with those of the mouthpart structure and the coiling pattern of the intestine in A. h. hemispinus and A. h. cinctus. Morphological distinction, coupled with different habitat and food preferences, supports the taxonomic elevation of the two hitherto subspecific populations of A. hemispinus to species.

A phenetic analysis of <i>Colletotrichum gloeosporioides</i> isolates from selected host plants

Colletotrichum gloeosporioides is a ubiquitous fungus which infects a wide variety of plants in tropical, sub-tropical and temperate regions. This fungus accounts for substantial economic losses through out the world via both preharvest and postharvest diseases. A phenetic analysis of C. gloeosporioides isolated from Capsicum frutescens, Carica papaya, Mangifera indica, Persea americana, Ficus religiosa and Hevea brasiliensis was carried out to identify sub-specific populations. A total of 40 isolates from these six host species were used. The overall similarity among different isolates of C. gloeosporioides was determined using culture, conidial and appressorial characteristics. According to the resulting phenogram, fungal isolates had divided into two distinct groups at the initial stage separating C. papaya isolates from the rest of the isolates. The subsequent branching has lead to separation of C. gloeosporioides isolates of different hosts into distinct groups. A high degree of similarity was observed among the isolates obtained from C. frutescens, H. brasiliensis and F. religiosa. Similarly, isolates of P. americana and M. indica appear to be morphologically more similar to each other. Further, the study confirms the cross infection potential of some C. gloeosporioides isolates and the presence of host specific populations Key Words: anthracnose; phenetic analysis; cross inoculation DOI: 10.4038/cjsbs.v38i2.1859 Cey. J. Sci. (Bio. Sci.) 38 (2): 57-66, 2009

Catálogo de los Megachilidae del Mediterráneo occidental (Hymenoptera, Apoidea). III. Anthidiini y Dioxyini

The present work is the third and last of three that compose a catalogue of the family Megachilidae in the western Mediterranean region. It includes the taxa of the tribes Anthidiini and Dioxyini (subfamily Megachilinae), their synonymies, discussion, when necessary, as well as their geographical distribution (Tables 1, 2, 3, 4). The results of our study indicate that the fauna of these tribes in the western Mediterranean is composed of 9 genera, 16 subgenera, 58 species in the Anthidiini and 6 genera and 15 species in the Dioxyini. Several species can be differentiated into subspecific populations adding up to a total that exceeds 90 subspecies, all of which are treated. Also, and with the catalogue of the Megachilidae of the western Mediterranean now complete (Ornosa et al. , 2006, 2007, this paper), the fauna of these Apoidea insects can be said to consist of 1 family, 2 subfamilies, 5 tribes, 30 genera, 65 subgenera, 423 species and 486 subspecies. Tables 5 and 6 give a synthesis of the biogeographical data.

MACROGEOGRAPHIC VOCAL VARIATION IN SUBSPECIES OF SWAMP SPARROW

Abstract Variation in song can play a central role in species and subspecies recognition among birds. The ability of individuals to distinguish between songs of their own versus songs of a different subspecies potentially strengthens local adaptation of subspecific populations. We investigated the degree of vocal divergence and discrimination between two subspecies of Swamp Sparrow (Melospiza georgiana) to examine how variation in song could influence behavioral response. We recorded songs of Southern (M. g. georgiana) and Coastal Plain (M. g. nigrescens) Swamp Sparrow males in Maryland and Delaware, respectively, and analyzed variation in syllable composition, repertoire size, trill rate, and frequency bandwidth. In addition to describing differences in song characteristics, we performed an estimate of local song type diversity that predicted larger population repertoires in M. g. nigrescens. We then broadcast recordings to evaluate male territorial responses to song and found that males reacted more str...

Strong population substructure is correlated with morphology and ecology in a migratory bat

Examining patterns of inter-population genetic diversity can provide valuable information about both historical and current evolutionary processes affecting a species. Population genetic studies of flying and migratory species such as bats and birds have traditionally shown minimal population substructure, characterized by high levels of gene flow between populations. In general, strongly substructured mammalian populations either are separated by non-traversable barriers or belong to terrestrial species with low dispersal abilities. Species with female philopatry (the tendency to remain in or consistently return to the natal territory) might show strong substructure when examined with maternally inherited mitochondrial DNA, but this substructure generally disappears when biparentally inherited markers are used, owing to male-mediated gene flow. Male-biased dispersal is considered typical for mammals, and philopatry in both sexes is rare. Here we show strong population substructure in a migratory bat species, and philopatry in both sexes, as indicated by concordance of nuclear and mtDNA findings. Furthermore, the genetic structure correlates with local biomes and differentiation in wing morphology. There is therefore a close correlation of genetic and morphological differentiation in sympatric subspecific populations of this mammalian species.

Mate choice theory and the mode of selection in sexual populations.

Indirect new data imply that mate and/or gamete choice are major selective forces driving genetic change in sexual populations. The system dictates nonrandom mating, an evolutionary process requiring both revised genetic theory and new data on heritability of characters underlying Darwinian fitness. Successfully reproducing individuals represent rare selections from among vigorous, competing survivors of preadult natural selection. Nonrandom mating has correlated demographic effects: reduced effective population size, inbreeding, low gene flow, and emphasis on deme structure. Characters involved in choice behavior at reproduction appear based on quantitative trait loci. This variability serves selection for fitness within the population, having only an incidental relationship to the origin of genetically based reproductive isolation between populations. The claim that extensive hybridization experiments with Drosophila indicate that selection favors a gradual progression of "isolating mechanisms" is flawed, because intra-group random mating is assumed. Over deep time, local sexual populations are strong, independent genetic systems that use rich fields of variable polygenic components of fitness. The sexual reproduction system thus particularizes, in small subspecific populations, the genetic basis of the grand adaptive sweep of selective evolutionary change, much as Darwin proposed.

A Molecular Marker Identifying Subspecific Populations of the Soybean Brown Stem Rot Pathogen, Phialophora gregata

ABSTRACT A molecular marker was developed to separate and identify subspecific populations of Phialophora gregata, the causal agent of soybean brown stem rot. A variable DNA region in the intergenic spacer of the nuclear rDNA was identified. Two specific primers flanking the variable region were developed for easy identification of the genotypes using polymerase chain reaction (PCR). These two specific primers amplified three DNA products. The three PCR products were used to separate isolates of P. gregata into distinct genotypes: A (1,020 bp), B (830 bp), and C (660 bp). Genotype C was found in isolates obtained from Adzuki beans from Japan, whereas all 292 isolates obtained from soybean and the 8 isolates from mung bean belonged to either genotype A or B. The original nondefoliating (type II) strain ATCC 11073 (type culture of P. gregata) belonged to genotype B. The difference between genotypes A and B was due only to an 188-bp insertion or deletion; genotype C, however, differs from genotypes A and B at 58 point mutations, in addition to the length difference. Isolates of both genotypes A and B were widespread in seven Midwestern states. Genotype A was found mostly in certain susceptible soybean cultivars like Sturdy and Pioneer 9305, whereas genotype B was found predominately in brown stem rot-resistant soybean cvs. Bell, IA 3003, and Seiben SS282N. The specific primers were also used to directly detect cultivar-preferential infection by the two genotypes in infected soybean stems growing in the same field. Data from direct detection in soybean stems showed that cultivar-preferential infection by the two genotypes of P. gregata was significant.

Subspecific morphological variation in the saddle-back tamarin (Saguinus fuscicollis).

Hershkovitz (Living New World, Volume 1. Chicago, University Press of Chicago, 1977, pp. 618-627, 634-666) identified 13 subspecies of Saguinus fuscicollis based on coat color variation on the head, neck, and shoulders. Other morphological differences among the subspecies are unknown. It has been suggested, however, that several of the taxa may be distinct at the specific level. In this report, we examine the level and pattern of facial morphological variation among the subspecific populations to evaluate their taxonomic status. Eleven facial measurements were recorded from the left side of 104 saddle-back tamarin crania. Significant morphological variation among the subspecies in facial heights and depths was detected with discriminant function analysis. Analyses of morphological differences between subspecies and among individual specimens relative to geographical and evolutionary distances (based on the metachromatic theory) were performed by using quadratic assignment procedures. These analyses indicate an absence of geographically related morphological variation across the species range while phylogenetic relationships are reflected in morphological similarities among groups and individuals. This finding is consistent with the formation of subspecific populations by relatively small founding populations budding off from a larger parent population, invading a new interfluvial basin, and then remaining relatively isolated, as suggested by Hershkovitz (Living New World Monkeys, Volume 1. University of Chicago Press, Chicago, 1977).

Methods for the Comparative Analysis of Variation Patterns

-Although comparisons of variation patterns with theoretical expectations and across species are playing an increasingly important role in systematics, there has been a lack of appropriate procedures for statistically testing the proposed hypotheses. We present a series of statistical tests for hypotheses of morphological integration and for interspecific comparison, along with examples of their application. These tests are based on various randomization and resampling procedures, such as Mantel's test with its recent extensions and bootstrapping. They have the advantage of avoiding the specific and strict distributional assumptions invoked by analytically-based statistics. The statistical procedures described include one for testing the fit of observed correlation matrices to hypotheses of morphological integration and a related test for significant differences in the fit of two alternative hypotheses of morphological integration to the observed correlation structure. Tests for significant similarity in the patterns and magnitudes of variance and correlation among species are also provided. [Morphometrics; comparative analysis; morphological integration; quadratic assignment procedures; Mantel's test; bootstrap.] Comparing observed patterns of morphometric variation to theories of morphological integration (Olson and Miller, 1958; Cheverud, 1982) and among species, or subspecific populations (Arnold, 1981; Riska, 1985), has been a largely ad hoc procedure. Previously, a large body of methods has been used to analyze variation patterns, including various forms of cluster analysis, factor analysis, principal components, multi-dimensional scaling, matrix correlations, and visual inspection. The results of such analyses were then discussed relative to some theory of variation patterns or compared between species or populations. These comparisons might either be verbal or quantitative, but tests of statistical significance were rarely employed. More recently, there has been an increase in statistical rigor in the field, particularly involving the use of quadratic assignment procedures (QAP; sometimes referred to as Mantel's test) (Mantel, 1967; Deitz, 1983; Dow and Cheverud, 1985; Smouse et al., 1986; Dow et al., 1987a, b; Hubert, 1987) for testing the statistical significance of matrix comparisons (Cheverud and Leamy, 1985; Lofsvold, 1986; Kohn and Atchley, 1988; Cheverud, 1989a; Wagner, 1989) and the use of confirmatory factor analysis (Zelditch, 1987, 1988) for testing hypotheses concerning levels and patterns of variation. These new methods allow statistical inference for hypotheses of morphological integration and for comparisons across species. We will describe the use of several of these newer methods, especially those using randomization, for testing hypotheses of morphological integration and interspecific comparison and provide brief examples of their use. The procedures described below can be used to rigorously test hypotheses concerning the causes of morphological variation and covariation patterns. A closely related set of procedures can be directed towards comparative, cross-taxon, analyses of variation and correlation patterns. The systematic study of distinction among group means is well known and extensively represented in the literature. However, systematic studies of variation patterns (as measured by a multivariate variance/covariance or correlation matrix) have been relatively rare. This has been due, in part, to a lack of relevant theory and appropriate systematic methodology. Important theoretical advances over the

Mitochondrial DNA polymorphism in three Antillean island populations of the fruit bat, Artibeus jamaicensis.

The Neotropical fruit bat, Artibeus jamaicensis, occurs throughout Latin America and on many islands in the Caribbean. Populations from Jamaica (in the Greater Antilles) to Barbados (in the Lesser Antilles) have been classified as a subspecies (A.j. jamaicensis) separate from that on the Lesser Antillean island of St. Vincent (A.j. schwartzi). Mitochondrial DNA (mtDNA) was isolated from 54 individuals collected on these islands, analyzed by digestion with restriction endonucleases, and the restriction sites were mapped. Three different mtDNA genotypes (16,000 +/- 200 bp) were identified: J-1 (16 animals from Jamaica, one from St. Vincent, 15 from Barbados), J-2 (two animals from Jamaica), and SV-1 (18 animals from St. Vincent, two from Barbados). The J-1 and J-2 genotypes were estimated to differ from each other by only 0.4%, but the SV-1 genotype differed from J-1 and J-2 by 8.1%-10.5%. The estimated sequence divergence between SV-1 and J-1 is unusually large for mammals that are regarded as conspecific. Restriction mapping showed that the differences among the genotypes (presence or absence of particular restriction sites) were located throughout the genome. The presence of the J-1 mtDNA genotype on Jamaica and on St. Vincent and Barbados (1,400 km away) demonstrates that maternal lineages in these bats are not necessarily confined to single islands or limited geographic regions. The presence of the J-1 mtDNA genotype within the A. j. schwartzi population on St. Vincent and the presence of the SV-1 genotype in two specimens of A. j. jamaicensis from Barbados document genetic exchange between subspecific populations on these islands, which are separated by 180 km of open water.

The Reproductive and Fat Body Cycles of the Lizard, Sceloporus grammicus disparilis

The Reproductive and Fat Body Cycles of the Lizard, Sceloporus grammicus disparilis

A Contact Zone Between Karyotypically Characterized Taxa of Uroderma Bilobatum (Mammalia: Chiroptera)

Baker, R. J., W. J. Bleier, and W. R. Atchley (Department of Biological Sciences and The Museum, Departments of Biological Sciences and Faculty of Statistics, Texas Tech University,,Lubbock, Texas 79409.) A contact zone between karyotypically characterized taxa of Uroderma bilobatum (Mammalia: Chiroptera) Syst. Zool. 24:133-142.-A total of 191 specimens of Peters' tent-making bat, Uroderma bilobatum, were collected from the zone where two chromosomal races, representing two subspecies, meet. Eighty-eight specimens had 2n = 38, four had 2n = 39, one had 2n = 40, one had 2n = 41, one had 2n = 42, 14 had 2n = 43, and 82 had 2n = 44. This chromosomal variation is best explained as resulting from between two cytotypes with the 2n = 38 and the 2n = 44 being the parental (pure) types, the 2n = 41 individual being of the F1 type and the 2n = 43, 42, 40, and 39 individuals representing backcross or F2 products. The two parental cytotypes were not found to be sympatric at any individual collecting station. The zone of is approximately 200 kilometers long on the Pacific versant of Honduras, eastern El Salvador and northwestern Nicaragua. Somne chromosomally intermediate individuals were reproductively active although the frequency of reproductive activity was not so great as in individuals with parental cytotypes. Measurements of the cranial and wing morphology of chromosomally intermediate individuals indicated that in general there was a correspondence between chromosome number and phenetic similarity to one or the other of the two parental stocks. Chromosomal and cranial and wing morphological data suggest that there is considerable gene flow between the two cytotypes and that chromosomal divergence has occurred in the absence of speciation. The magnitude of chromosomal differentiation between the two subspecies serves as a caveat to those cases where specific recognition is based on chromosomal distinctness of allopatric samples. [Karyotypes; Chiroptera; Uroderma.] Although there have been numerous studies on the divergence of subspecific populations of mammals, such studies have been concerned primarily with the description of size (cranial and external measurements) and pelage color variations that serve as a basis for trinominal application (for a critique see Lidicker, 1962). Such studies have documented that many mammalian species can be subdivided into morphologically distinct units, but they have failed to reveal the nature of the interactions at zones of contact between such units. However, when two subspecific units come into contact, it is the interaction between the units that determines their evolutionary future. Perhaps the greatest factor that inhibits studies of contact zones is that the degree of morphological divergence is insufficient to identify all members of the respective populations, plus F1 and backcross individuals. In the tent-making bat, Uroderma bilobatum, the subspecies U. b. davisi and U. b. convexum are easily identified by chromosomal features (Baker et al., 1972). The degree of chromosomal divergence is also adequate to identify presumed F1 and backcross individuals. The present study was conducted to determine the nature of the contact zone between the subspecies davisi and convexum in hopes that such a study would help elucidate the nature and significance of such zones in mammals. In the following discussion the term hybridization refers to successful reproduction between two unlike parental stocks (in this case chromosomally characterized) and is not meant to infer specific status (or the lack of it) to the taxa involved. Cytotype

Experimental crossing of Aedes (S.) polynesiensis Marks and A. scutellaris malayensis Colless (Diptera: Culicidae).

The Aedes (S.) scutellaris subgroup is comprised of many species and possible subspecific populations distributed throughout a vast area of the South and Central Pacific and southeastern Asia. The genetic relationships of most of these populations are unknown, as experimental cross breeding has been carried out with relatively few of them. This paper presents the results of such studies with Aedes scutellaris malayensis and 3 populations of A. polynesiensis (from Samoa, Tahiti, and Taiaro). The opposite sexesof the 2 specieswere attracted to one another in precopulatory mating activity. In mating choice experiments, the females were inseminated more readily by their own males than by males of the opposite species; however, under proper conditions and when no choice was possible, A. polynesiensis females were inseminated about as frequently by A. s. maloyensis males as were A. s. malayensis females. There was no hatching of any of the eggs produced by the cross-inseminated females of all 3 strains of A. polynesiensis . Cross-insemination of A. s. malayensis females by Tahiti and Taiaro A. polynesiensis males occurred readily, but eggs laid by these females did not hatch. In contrast, although a relatively small proportion of A. s. malayensis females were inseminated by Samoan A. polynesiensis males, these females produced viable eggs, and most of the F1 larvae were reared to the adult stage. It was not possible to obtain an F2 generation by inbreeding the F1 hybrids. Only a few of the F2 eggs hatched. Backcrossing of F1 (M♀ × P♂) hybrids to A. polynesiensis and A. s. malayensis females was unsuccessful. However, backcrossing of the F1 females to A. s. malayensis males was possible, and beginning with this 1st generation of backcross progeny, 2 lines of successivebackcrosses were carried out, one to A. s. malayensis males and the other to A. s. malayensis females. As these progressed, there was an increase in viable egg production, and by the 5th backcross, viable egg production exceeded that of control A. s. malayensis females. Also, inbreeding of the 3rd and 4th backcross generations was successful. There was no hatching of eggs from A. polynesiensis females inseminated by males of the 3rd and 4th backcross generations. Conversely, the females of these generations were able to produce viable eggs after insemination by A. polynesiensis males. It is concluded that A. s. malayensis and A. polynesiensis are specifically distinct. However, introgressive hybridization is possible between some, although not all of the populations belonging to these species. If this is true of species which occur at the extreme eastern and western areas of the A. scutellaris subgroup range, it seems possible that hybrid populations exist in nature and that some of the recognized species are polytypic.