The litoria ewingi complex (Anura : Hylidae) in south-eastern Australia V. Interactions between northern L. ewingi and adjacent taxa

1978 ◽  
Vol 26 (1) ◽  
pp. 175 ◽  
Author(s):  
GF Watson ◽  
MJ Littlejohn
Keyword(s):  
Small Area ◽  
Character Displacement ◽  
Reproductive Character Displacement ◽  
Genetic Compatibility ◽  
Natural Interaction ◽  
Call Structure ◽  
Environmental Features ◽  
Mating Call ◽  
Eastern Australia ◽  
High Level

A small area of overlap with hybridization characterizes the interaction between northern L. ewingi and L. paraewingi. Although significant levels of postmating isolation exist between the taxa, no evidence of reproductive character displacement in mating-call structure is apparent within the contact zone. No obvious environmental features appear to correlate with the position of the zone. Northern L. ewingi and L. verreauxi alpina also form a hybrid zone where their ranges meet, and the position of the zone appears to be correlated with altitude. The taxa are characterized by a high level of genetic compatibility and no mating-call differentiation is evident. However, despite hybridization with adjacent taxa, the distinctness of northern L. ewingi is maintained away from the areas of interaction, and hence it is considered specifically distinct from L. paraewingi and L. v. alpina. No natural interaction between northern L. ewingi and L. ewingi has been located. However, they are considered to be conspecific because of: their morphological resemblance; the high level of genetic compatibility between them; and, the similarity of each of their interactions with L. paraewingi and with L. v. alpina.

The litoria ewingi complex (Anura : Hylidae) in south-eastern Australia IV. Variation in mating-call structure across a narrow hybrid zone between L. ewingi ad L.paraewingi

1976 ◽  
Vol 24 (2) ◽  
pp. 283 ◽  
Author(s):  
MJ Littlejohn
Keyword(s):  
Hybrid Zone ◽  
Parental Species ◽  
Character Displacement ◽  
Pulse Repetition ◽  
Reproductive Character Displacement ◽  
Genetic Incompatibility ◽  
Call Structure ◽  
Mating Call ◽  
Eastern Australia ◽  
Mating Calls

The presence of mating calls characteristic of both parental species, and of intermediate calls, within the zone of contact between L. ewingi and L. paraewingi supports the earlier interpretation that the interaction is an overlap with hybridization. Pulse repetition rates are similar throughout the transect, and there are no clear indications of reproductive character displacement within the hybrid zone, even though marked one-way genetic incompatibility is present. However, calls from close allopatry are more distinctive than those from distant allopatry, mainly in pulses per repeated note (a meristic character reflecting differences in note duration), suggesting that the effects of reinforcing selection may be accumulating in the proximity of the zone of interaction.

The Litoria ewingi Complex (Anura:Hylidae) in South-Eastern Australia VIII.* Hybridization between L. ewingi and L. verreauxi alpina in the Mount Baw Baw Area, South Central Victoria

1985 ◽  
Vol 33 (2) ◽  
pp. 143 ◽  
Author(s):  
GF Watson ◽  
MJ Littlejohn ◽  
DF Gartside ◽  
JJ Loftus-Hills
Keyword(s):  
Northern Slope ◽  
Blood Proteins ◽  
Genetic Compatibility ◽  
Hybrid Swarm ◽  
Geographic Ranges ◽  
Central Victoria ◽  
South Central ◽  
Eastern Australia ◽  
High Level

Contacts between the geographic ranges of the widely distributed species, Litoria ewingi, and the montane-adapted taxon, L. verreauxi alpina, occur at about 1200 m on the Great Dividing Range in south central Victoria. Data for adult morphology, genetic compatibility, blood proteins (haemoglobins and transferrins), and structure of male advertisement calls, were obtained from seven populations at altitudes between 640 m and 1450 m in the region of the Mount Baw Baw Plateau. The results indicate that hybrids are present at intermediate altitudes (1140-1270 m), but that the nature of the interaction differs between overlap of parental taxa together with recombination products on the south-westem slope (the Baw Baw transect), and a hybrid swarm on the northern slope of the Mount Baw Baw plateau. Results of in vitro crosses (female L, ewingi by male L. v. alpina) indicate that there is a high level of genetic compatibility between the taxa. Estimates of the width of the hybrid zone on the Baw Baw transect vary from less than 4 km for morphology and calls, to between 10 and 24 km for blood proteins.

Contact hybridization in the Crinia laevis complex (Anura : Leoptodactylidae)

1971 ◽  
Vol 19 (1) ◽  
pp. 85 ◽  
Author(s):  
MJ Littlejohn ◽  
GF Watson ◽  
JJ Loftus-Hills
Keyword(s):  
Environmental Factors ◽  
Hybrid Zone ◽  
Acoustic Analysis ◽  
Backcross Progeny ◽  
Geographic Ranges ◽  
Call Structure ◽  
Mating Call ◽  
High Level ◽  
Western Victoria ◽  
Different Parts

Mating-call structure was used to determine the nature and extent of an interaction between the two morphologically indistinguishable taxa, C. laevis and C. victoriana, where their geographic ranges contact in south-western Victoria. Intermediacy of mating-call structure was detected in a zone about 115 km long and less than 2 km wide. Acoustic analysis of call samples from six localities indicated that hybrids, backcross progeny, and one or both parental types were present in this zone. Results of reciprocal artificial hybridization tests between allopatric individuals of the two taxa showed that there was a high level of interfertility in both combinations, but with slightly reduced survival to metamorphosis. Presumed backcrosses using males from the hybrid zone resulted in a higher level of survival to metamorphosis. The zone does not coincide with any conspicuous ecotone and presumably represents a complex balance point with various environmental factors contributing to a greater or lesser extent in different parts of the contact. In spite of this lack of reproductive isolation, the narrowness of the zone and the presumed antiquity of the contact demonstrate that the taxa will continue to maintain their distinctness, and should retain their specific status.

The Litoria ewingi Complex (Anura: Hylidae) in South-Eastern Australia VII.* Mating Call Structure and Gentic Compatibility across a Narrow Hybrid Zone between L. ewingi and L. parawingi

1983 ◽  
Vol 31 (2) ◽  
pp. 193 ◽  
Author(s):  
MJ Littlejohn ◽  
GF Watson
Keyword(s):  
Hybrid Zone ◽  
Parental Species ◽  
Allopatric Population ◽  
Minimum Width ◽  
Call Structure ◽  
Allopatric Populations ◽  
South Eastern ◽  
Mating Call ◽  
Eastern Australia

On the basis of the number of pulses per repeated note and of repeated notes per call for individual males, the interaction between Litoria ewingi and L. paraewingi in the region of the Tallarook (northern) transect is interpreted as a transitional hybrid zone, with populations consisting of hybrids and individuals of only one or other parental species. The Tallarook transect thus differs from the Glenburn (southern) transect, which is considered to be an overlap of both parental species together with recombination products. The minimum width of the zone in the area of the Tallarook transect is estimated to be 25 km, compared with 5 km for the Glenburn transect. Levels of partial and total anophthalmia were assessed in progeny from in vitro crosses involving a total of 27 males from both transects whose calls had been recorded and analysed, and females of L. ewingi from adjacent allopatry (a measure of the genetic representation of L. paraewingi). The results are, with one exception, consistent with the mating-call structure of these males. As was found with the Glenburn transect, calls of males of L. paraewingi from an allopatric population on the Tallarook transect close to the zone of interaction are more distinctive from calls of L. ewingi in pulses per repeated note than are those of distant allopatric populations of L. paraewingi. This finding is consistent with the suggestion that the products of reinforcing selection may be accumulating near the zone of interaction.

Acoustic analysis of an intergrade zone between two call races of the Limnodynastes tasmaniensis complex (Anura : Leptodactylidae) in south-eastern Australia

1975 ◽  
Vol 23 (1) ◽  
pp. 113 ◽  
Author(s):  
MJ Littlejohn ◽  
JD Roberts
Keyword(s):  
Acoustic Analysis ◽  
Secondary Contact ◽  
Ecological Gradient ◽  
North Central ◽  
Call Structure ◽  
Central Victoria ◽  
South Eastern ◽  
Eastern Australia ◽  
Mating Calls ◽  
South Eastern Australia

Mating calls of the northern and southern call races of the L. tasmaniensis complex are described. Analysis of call structure along a transect across the main contact between these allopatric forms in north central Victoria indicates that there is a zone of intergradation between 90 and 135 km wide, about 215 km long and with a north-westerly orientation. The interaction is interpreted as a secondary contact in which there is hybrid or recombinant superiority along a subtle ecological gradient.

Cryptic Diversity and Sexual Selection

2020 ◽  
pp. 447-471
Author(s):  
Matthias Galipaud ◽  
Loïc Bollache ◽  
Clément Lagrue
Keyword(s):  
Sexual Selection ◽  
Morphological Traits ◽  
Character Displacement ◽  
Secondary Contact ◽  
Cryptic Diversity ◽  
Reproductive Character Displacement ◽  
Behavioral Traits ◽  
Genetic Techniques ◽  
Existing Data

Recent advances in molecular and genetic techniques have revealed tremendous hidden genetic diversity in plants and animals. Crustaceans are no exception and, in fact, present one of the highest levels of cryptic diversity among the metazoans. Beyond the importance of such discovery and its multiple implications for taxonomy and ecology, it is now timely to investigate the potential causes of cryptic diversity. This chapter reviews the theoretical and experimental literature, seeking evidences for a relationship between sexual selection and cryptic diversity in crustaceans. It proposes three scenarios for the role of sexual selection on the origin and maintenance of pre-mating isolation and genetic divergence among crustacean populations, and suggests ways to discriminate among them experimentally or using existing data. Assuming that taxonomic identification is largely based on differences in sexually selected morphological traits, it also reviews evidence for a cryptic action of sexual selection on crustacean phenotypes. Specifically, if sexual selection acts primarily on chemical, visual, or behavioral traits, it is likely that allopatric crustacean populations remain morphologically similar even when they are reproductively isolated. This review shows that the strength of sexual selection likely differs among allopatric populations but does not seem to consistently induce pre-mating isolation (e.g. as in copepods and amphipods). Research is now needed to try to identify general patterns and determine the role of sexual selection on pre-mating isolation after secondary contact between populations, through reinforcement and reproductive character displacement.

Asymmetric acoustic signal recognition led to asymmetric gene flow between two parapatric frogs

2020 ◽  
Author(s):  
Yu-Wei Hsiao ◽  
Hui-Yun Tseng ◽  
Hung Ngoc Nguyen ◽  
Si-Min Lin
Keyword(s):  
Gene Flow ◽  
Contact Region ◽  
Character Displacement ◽  
Secondary Contact ◽  
Genetic Introgression ◽  
Genetic Integrity ◽  
Signal Recognition ◽  
Reproductive Character Displacement ◽  
Reproductive Character ◽  
Behavioural Experiments

Abstract Correct discrimination between courtship signals could help to maintain genetic integrity between closely related species. However, asymmetric usage of signals might cause asymmetric gene flow across the contact zone. Buergeria choui and B. otai are sibling-species with a parapatric distribution pattern in Taiwan, having two narrow contact zones on the east and west sides of the island. Combining behavioural experiments with genome-wide RAD-seq analyses, we test whether the ability of signal recognition influences genetic introgression across their species boundary. The playback experiments show that all B. choui populations respond strongest to their own ‘cricket’ trills, while the western population of B. otai have evolved a strong level of reproductive character displacement by showing the inclusive usage of the unique ‘chicken’ signals. In contrast, the eastern B. otai population uses both ‘chicken’ and ‘cricket’ trills, and has a stronger preference for the latter. The weak reproductive character displacement in the eastern population has led to asymmetry genetic introgression from B. choui toward B. otai. Our results support the prediction that a more specialized signal-user, compared to its sibling, generalized signal-user, might have a higher probability of maintaining their genetic integrity in the secondary contact region.

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