Systematic Status of a Midwater Population of Freshwater Sculpin (Cottus) from Lake Washington, Seattle, Washington

1975 ◽  
Vol 32 (1) ◽  
pp. 21-28 ◽  
Author(s):  
K. W. Larson ◽  
G. W. Brown Jr.
Keyword(s):  
Reproductive Isolation ◽  
Canal System ◽  
Systematic Status ◽  
Close Relationship ◽  
Lake Washington ◽  
Freshwater Sculpin

A population of freshwater sculpin from Lake Washington differs from other species of the typically benthic genus Cottus in that individuals migrate nightly to the surface and midwaters. Individuals are phenotypically and biochemically similar to Cottus aleuticus, but have a longer, more terete body, a larger cephalic pore and canal system, shorter pelvic fins, and a higher frequency of individuals with seven branchiostegal rays per side.A close relationship between the Lake Washington population and C. aleuticus seems indicated because of their phenotypic and biochemical similarities and because of the existence of individuals in other Northwest lakes that appear intermediate in character between C. aleuticus and the Lake Washington population. The decision as to the specific status of the Lake Washington population is deferred until more is known of its degree of reproductive isolation from C. aleuticus and of the existence of these possibly intermediate populations.

Revision of the systematic status of Helminthoglypta walkeriana morroensis (Hemphill, 1911) (Gastropoda: Pulmonata)

Zootaxa ◽  
2004 ◽  
Vol 616 (1) ◽  
pp. 1
Author(s):  
BARRY ROTH ◽  
JEFF TUPEN
Keyword(s):  
Reproductive Isolation ◽  
Biological Species ◽  
Taxonomic Significance ◽  
Central California ◽  
Shell Form ◽  
Systematic Status ◽  
San Luis ◽  
Terrestrial Snails ◽  
The City

Globose-shelled to depressed-helicoid terrestrial snails of the subgenus Helminthoglypta (Charodotes) occur from the vicinity of Morro Bay to the City of San Luis Obispo in San Luis Obispo County, central California, USA. Populations with intensely papillose shells largely or entirely lacking incised spiral sculpture, originally described as "Helix var. morroensis," have been regarded as either a subspecies of Helminthoglypta walkeriana (Hemphill, 1911) or an infrasubspecific variation without taxonomic significance. Shell form variation is distributed as one would expect if the two major aggregations of individuals were reproductively isolated, biological species, H. walkeriana and H. morroensis (Hemphill, 1911). Differing penial morphology is also consistent with reproductive isolation. The two species appear to be allopatric.

Reproductive Isolation Between Isozyme Groups of Glycine tomentella (Leguminosae), and Spontaneous Doubling in Their Hybrids

1986 ◽  
Vol 34 (5) ◽  
pp. 523 ◽  
Author(s):  
MJ Doyle ◽  
JE Grant ◽  
AHD Brown
Keyword(s):  
Chromosome Number ◽  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Gene Pools ◽  
Single Chromosome ◽  
Glycine Tomentella ◽  
Hybrid Plants ◽  
Genomic Divergence ◽  
Close Relationship ◽  
Mother Cells

Previous studies of infraspecific isozyme variation in Glycine tornentella have recognised five tetraploid (TI, T2, ... T5) and seven diploid (Dl, D2, ... D7) subspecific groups. This report analyses the meiosis in pollen mother cells of 31 new tetraploid hybrids, 10 diploid hybrids and three diploid by tetraploid combinations. A close relationship, over the range of diversity, was observed between isozyme similarity of the parents of hybrids and chromosome pairing at meiosis. In general, hybrids between parents belonging to the same isozyme group were fertile whereas hybrids between groups were sterile. In the tetraploids, the fertility of interregional hybrids when the accessions belonged to the same group confirmed the widespread distribution of groups T1 and T4. Alternatively, the sterility of intraregional hybrids between groups showed that groups can coexist and remain as separate gene pools. Each isozyme group apparently had a single chromosome number (TI and T5 had 2n = 78; T2, T3 and T4 had 2n = 80). Some otherwise sterile hybrid plants produced rare progeny with elevated chromosome num- ber, probably from the functioning of unreduced male and female gametes. Considerable genomic divergence was apparent from the hybrids between diploid groups, comparable with that found between recognised Glycine species. Again isozyme groups had a characteristic chromosome number (Dl and D2 had 2n = 38, the remainder had 2n = 40). Thus reproductive isolation through reduced formation of bivalents at meiosis operated both between and within cytotypes (2n = 38, 40, 78, 80) of G. tornentella. The pattern of hybrid sterility was as predicted from the analysis of isozyme similarity, confirming the grouping as a meaningful classification within this diverse species.

scholarly journals Is Spizella Taverneri a Species or a Subspecies?

The Condor ◽  
2001 ◽  
Vol 103 (2) ◽  
pp. 418-419 ◽  
Author(s):  
Ernst Mayr ◽  
Ned K. Johnson
Keyword(s):  
Reproductive Isolation ◽  
Pair Formation ◽  
Species Status ◽  
Loss Of Information ◽  
Allopatric Distribution ◽  
Close Relationship ◽  
Spizella Breweri

AbstractBased on distributional, ecologic, morphologic, and vocal data, Klicka et al. (1999) argued in favor of species status for the form taverneri, long regarded as a subspecies of the Brewer's Sparrow (Spizella breweri). For several reasons we disagree with their conclusion: lack of evidence for the reproductive isolation of taverneri from breweri, loss of information on the close relationship and allopatric distribution of the two taxa that would accompany their elevation to species, and violation of the principle of taxonomic balance. Until the demonstration of vocal or display differences relevant to pair formation and maintenance, taverneri and breweri are best regarded as reproductively compatible subspecies.

scholarly journals Rapid Evolution of Assortative Fertilization between Recently Allopatric Species of Drosophila

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Yasir H. Ahmed-Braimah ◽  
Bryant F. McAllister
Keyword(s):  
Reproductive Isolation ◽  
Phylogenetic Analyses ◽  
Hybrid Sterility ◽  
Rapid Evolution ◽  
Fertilization Success ◽  
Good Resolution ◽  
Genetic Changes ◽  
Close Relationship ◽  
Virilis Group ◽  
Consequent Reduction

The virilis group of Drosophila represents a relatively unexplored but potentially useful model to investigate the genetics of speciation. Good resolution of phylogenetic relationships and the ability to obtain fertile hybrid offspring make the group especially promising for analysis of genetic changes underlying reproductive isolation separate from hybrid sterility and inviability. Phylogenetic analyses reveal a close relationship between the sister species, Drosophila americana and D. novamexicana, yet excepting their contemporary allopatric distributions, factors that contribute to reproductive isolation between this species pair remain uncharacterized. A previous report has shown reduced progeny numbers in laboratory crosses between the two species, especially when female D. novamexicana are crossed with male D. americana. We show that the hatch rate of eggs produced from heterospecific matings is reduced relative to conspecific matings. Failure of eggs to hatch, and consequent reduction in hybrid progeny number, is caused by low fertilization success of heterospecific sperm, thus representing a postmating, prezygotic incompatibility. Following insemination, storage and motility of heterospecific sperm is visibly compromised in female D. novamexicana. Our results provide evidence for a mechanism of reproductive isolation that is seldom reported for Drosophila species, and indicate the rapid evolution of postmating, prezygotic reproductive barriers in allopatry.

Minding the Close Relationship

1999 ◽  
Author(s):  
John H. Harvey ◽  
Julia Omarzu
Keyword(s):  
Close Relationship

The Solution Strategy as an Indicator of the Developmental Stage of Preschool Children’s Mental-Rotation Ability

2010 ◽  
Vol 31 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Claudia Quaiser-Pohl ◽  
Anna M. Rohe ◽  
Tobias Amberger
Keyword(s):  
Preschool Children ◽  
Mental Rotation ◽  
Latent Class ◽  
Preschool Age ◽  
Stage Model ◽  
Solution Strategy ◽  
Thinking Aloud ◽  
Transition Analysis ◽  
Solution Strategies ◽  
Close Relationship

The solution strategies of preschool children solving mental-rotation tasks were analyzed in two studies. In the first study n = 111 preschool children had to demonstrate their solution strategy in the Picture Rotation Test (PRT) items by thinking aloud; seven different strategies were identified. In the second study these strategies were confirmed by latent class analysis (LCA) with the PRT data of n = 565 preschool children. In addition, a close relationship was found between the solution strategy and children’s age. Results point to a stage model for the development of mental-rotation ability as measured by the PRT, going from inappropriate strategies like guessing or comparing details, to semiappropriate approaches like choosing the stimulus with the smallest angle discrepancy, to a holistic or analytic strategy. A latent transition analysis (LTA) revealed that the ability to mentally rotate objects can be influenced by training in the preschool age.

Speeded Paper-Pencil Sustained Attention and Mental Speed Tests

2008 ◽  
Vol 29 (4) ◽  
pp. 205-216 ◽  
Author(s):  
Stefan Krumm ◽  
Lothar Schmidt-Atzert ◽  
Kurt Michalczyk ◽  
Vanessa Danthiir
Keyword(s):  
Sustained Attention ◽  
Time Pressure ◽  
Factor Model ◽  
Higher Order ◽  
Future Research ◽  
Perceptual Speed ◽  
Speed Factor ◽  
Close Relationship ◽  
Task Processing ◽  
Order Factor

Mental speed (MS) and sustained attention (SA) are theoretically distinct constructs. However, tests of MS are very similar to SA tests that use time pressure as an impeding condition. The performance in such tasks largely relies on the participants’ speed of task processing (i.e., how quickly and correctly one can perform the simple cognitive tasks). The present study examined whether SA and MS are empirically the same or different constructs. To this end, 24 paper-pencil and computerized tests were administered to 199 students. SA turned out to be highly related to MS task classes: substitution and perceptual speed. Furthermore, SA showed a very close relationship with the paper-pencil MS factor. The correlation between SA and computerized speed was considerably lower but still high. In a higher-order general speed factor model, SA had the highest loading on the higher-order factor; the higher-order factor explained 88% of SA variance. It is argued that SA (as operationalized with tests using time pressure as an impeding condition) and MS cannot be differentiated, at the level of broad constructs. Implications for neuropsychological assessment and future research are discussed.

How Can We Explain a Close Relationship?

PsycCRITIQUES ◽  
2012 ◽  
Vol 57 (41) ◽  
Author(s):  
Victor Cicirelli
Keyword(s):  
Close Relationship
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