Reproduction and feeding habits of the highly seasonal Brachyhypopomus bombilla (Gymnotiformes: Hypopomidae) from southern Brazil with evidence for a dormancy period

The reproductive biology and feeding habits of the hypopomid Brachyhypopomus bombilla were studied. The species has seasonal behavior, with breeding and feeding activity occurring mostly during the Southern Hemisphere spring and summer. We defined fractional spawning for the species and a relative fecundity similar to those previously reported for other gymnotiform species. According to the analysis of the food items, B. bombilla was included in the trophic category invertivorous, feeding mainly on autochthonous insects. The reproductive periods of males and females as well as female feeding activity were significantly related to the photoperiod. During a period of 5?months, when the lowest water temperatures and shortest photoperiod were recorded, all the specimens of B. bombilla were found buried in the muddy bottom of the creek, with lower electric organ discharge activity, empty stomachs, and gonads in early stages of the maturation process. This period, herein defined as a dormancy period, is reported here for the first time for a species of the Gymnotiformes order.     

Swimming Patterns Associated with Foraging in Phylogenetically and Ecologically Diverse American Weakly Electric Teleosts (Gymnotiformes)

The backwards swimming behavior exhibited by American weakly electric fishes (Gymnotiformes) is thought to be an important component of foraging, particularly in the electrolocation of prey items. Previous studies of Eigenmannia virescens and Apteronotus albifrons have shown that backwards swimming appears to allow a fish to scan a potential prey item across its cutaneous electroreceptor array, then put itself in position for a short, forward lunge preceding ingestion. Adult gymnotiforms exhibit considerable variation in size, shape, and electric organ characteristics. For example, gymnotiforms produce either a wave or a pulse electric organ discharge (EOD). Given this variation, we ask whether the results reported previously can be completely generalized to all gymnotiforms. To address this question we observed the foraging patterns of phylogenetically and ecologically distinct gymnotiforms: three wave species, E. virescens, A. albifrons and Sternopygus macrurus; and three pulse species, Gymnotus carapo, Brachyhypopomus cf. brevirostris, and Rhamphichthys rostratus. Electric organ placement and body shape were also noted in these species to determine if morphological differences correlate with variations in foraging behaviors. Results demonstrate that following prey detection the wave species examined primarily swim backwards during prey approach, prior to lunging forward and ingesting prey. This result is similar to previous findings. In contrast, the pulse species examined detect, approach, and ingest prey primarily in the forward direction, swimming backwards only to reposition themselves.     

Two new species and a new subgenus of toothed Brachyhypopomus electric knifefishes (Gymnotiformes,Hypopomidae) from the central Amazon and considerations pertaining to the evolution of a monophasic electric organ discharge

We describe two new, closely related species of toothed Brachyhypopomus (Hypopomidae: Gymnotiformes: Teleostei) from the central Amazon basin and create a new subgenus for them. Odontohypopomus, new subgenus of Brachyhypopomus, is diagnosed by (1) small teeth present on premaxillae; (2) medialmost two branchiostegal rays thin with blades oriented more vertically than remaining three rays; (3) background color in life (and to lesser extent in preservation) distinctly yellowish with head and sides peppered with small, widely spaced, very dark brown stellate chromatophores that greatly contrast with light background coloration; (4) a dark blotch or bar of subcutaneous pigment below the eye; (5) electric organ discharge waveform of very long duration (head-positive phase approx. 2 milliseconds or longer, head-negative phase shorter or absent) and slow pulse repetition rate (3–16 Hz). The type species of the new subgenus, Brachyhypopomus (Odontohypopomus) walteri sp. n., is diagnosed by the following additional character states: (1) subcutaneous dark pigment at base of orbit particularly prominent, (2) body semi-translucent and nearly bright yellow background coloration in life, (3) a biphasic electric organ discharge (EOD) waveform of very long duration (between 3.5 and 4 milliseconds at 25° C) with head-positive first phase significantly longer than second head-negative phase in both sexes. Brachyhypopomus (Odontohypopomus) bennetti sp. n. is diagnosed by two character states in addition to those used to diagnose the subgenus Odontohypopomus: (1) a deep electric organ, visible as large semi-transparent area, occupying approximately 14–17% body depth directly posterior to the abdominal cavity in combination with a short, but deep, caudal filament, and (2) a monophasic, head-positive EOD waveform, approximately 2.1 milliseconds in duration in both sexes. These are the only described rhamphichthyoid gymnotiforms with oral teeth, and Brachyhypopomus bennetti is the first Brachyhypopomus reported to have a monophasic (head-positive) EOD waveform. Unlike biphasic species, the waveform of its EOD is largely unaffected by tail damage from predators. Such injuries are common among specimens in our collections. This species’ preference for floating meadow habitat along the major channels of the Amazon River basin may put it at particularly high risk of predation and “tail grazing.”     

Waveform discrimination in a pair of pulse-generating electric fishes

Studies of pulse-type gymnotiform electric fishes have suggested that electric organ discharge waveforms (EODw) allow individuals to discriminate between conspecific and allospecific signals, but few have approached this experimentally. Here we implement a phase-locked playback technique for a syntopic species pair, Brachyhypopomus gauderio and Gymnotus omarorum. Both species respond to changes in stimulus waveform with a transitory reduction in the interpulse interval of their self-generated discharge, providing strong evidence of discrimination. We also document sustained rate changes in response to different EODws, which may suggest recognition of natural waveforms.     

Tight hormonal phenotypic integration ensures honesty of the electric signal of male and female Brachyhypopomus gauderio

Hormones mediate sexually selected traits including advertisement signals. Hormonal co-regulation links the signal to other hormonally-mediated traits such that the tighter the integration, the more reliable the signal is as a predictor of those other traits. Androgen administration increases the duration of the communication signal pulse in both sexes of the electric fish Brachyhypopomus gauderio. To determine whether the duration of the signal pulse could function as an honest indicator of androgen levels and other androgen-mediated traits, we measured the variation in sex steroids, signal pulse duration, and sexual development throughout the breeding season of B. gauderio in marshes in Uruguay. Although the sexes had different hormone titres and signal characteristics, in both sexes circulating levels of the androgens testosterone (T) and 11-ketotestosterone (11-KT) were strongly related to signal pulse duration. Consequently, signal pulse duration can serve as an honest indicator of circulating androgens in males and females alike. Additionally, through phenotypic integration, signal pulse duration also predicts other sexual traits directly related to androgen production: gonad size in males and estradiol (E2) levels in females. Our findings show that tight hormonal phenotypic integration between advertisement signal and other sex steroid-mediated traits renders the advertisement signal an honest indicator of a suite of reproductive traits.     

Testosterone and 11-ketotestosterone have different regulatory effects on electric communication signals of male Brachyhypopomus gauderio

The communication signals of electric fish can be dynamic, varying between the sexes on a circadian rhythm and in response to social and environmental cues. In the gymnotiform fish Brachyhypopomus gauderio waveform shape of the electric organ discharge (EOD) is regulated by steroid and peptide hormones. Furthermore, EOD amplitude and duration change on different timescales and in response to different social stimuli, suggesting that they are regulated by different mechanisms. Little is known about how androgen and peptide hormone systems interact to regulate signal waveform. We investigated the relationship between the androgens testosterone (T) and 11-ketotestosterone (11-KT), the melanocortin peptide hormone α-MSH, and their roles in regulating EOD waveform of male B. gauderio. Males were implanted with androgen (T, 11-KT, or blank), and injected with α-MSH before and at the peak of androgen effect. We compared the effects of androgen implants and social interactions by giving males a size-matched male stimulus with which they could interact electrically. Social stimuli and both androgens increased EOD duration, but only social stimuli and 11-KT elevated amplitude. However, no androgen enhanced EOD amplitude to the extent of a social stimulus, suggesting that a yet unidentified hormonal pathway regulates this signal parameter. Additionally, both androgens increased response of EOD duration to α-MSH, but only 11-KT increased response of EOD amplitude to α-MSH. Social stimuli had no effect on EOD response to α-MSH. The finding that EOD amplitude is preferentially regulated by 11-KT in B. gauderio may provide the basis for independent control of amplitude and duration.     

Reproductive morphology of the deep-sea protobranch bivalves Yoldiella ecaudata,Yoldiella sabrina,and Yoldiella valettei (Yoldiidae) from the Southern Ocean

The protobranch bivalves of the Southern Ocean are poorly understood ecologically, despite their high abundances in soft sediments from the shelf to the deep sea. The subclass has a long evolutionary history predating the formation of the polar front, and knowledge of their reproductive biology is key to understanding better their successful radiation into the Southern Ocean, and within deep-sea basins. In this study, we for the first time investigate the reproductive morphology of three deep-water protobranchs; Yoldiella ecaudata from 500 m in the Amundsen Sea; Y. sabrina from between 200 and 4,730 m in the Amundsen Sea, Scotia Sea, and South Atlantic; and Y. valettei from 1,000 m in the Scotia Sea. All three species demonstrate evidence of lecithotrophic larval development with maximum oocyte size of 130.4, 187.9, and 120.6 µm in Y. ecaudata, Y. sabrina, and Y. valettei, respectively, further supported by prodissoconch I measurements. There is evidence for simultaneous hermaphroditism in Y. valettei. Asynchronous oocyte development within specimens of Y. ecaudata and Y. valettei is described, and also between populations of Y. sabrina separated by depth. The reproductive characteristics, comparable to those of North Atlantic deep-sea protobranch species, are discussed in the context of the cold thermally stable conditions prevailing on the deep-Antarctic continental shelf and deep sea. The requirement for reclassification of this complex subclass is also discussed in relation to observed soft anatomy and shell characteristics.     

X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus

Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X₁X₁X₂X₂/X₁X₂Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X₁X₁X₂X₂/X₁X₂Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X₁X₁X₂X₂/X₁X₂Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X₁X₁X₂X₂/X₁X₂Y system may represent sex chromosomes turnover events in Gymnotiformes.     

Hormone‐mediated modulation of the electromotor CPG in pulse‐type weakly electric fish. Commonalities and differences across species

Like stomatogastric activity in crustaceans, vocalization in teleosts and frogs, and locomotion in mammals, the electric organ discharge (EOD) of weakly electric fish is a rhythmic and stereotyped electromotor pattern. The EOD, which functions in both perception and communication, is controlled by a two‐layered central pattern generator (CPG), the electromotor CPG, which modifies its basal output in response to environmental and social challenges. Despite major anatomo‐functional commonalities in the electromotor CPG across electric fish species, we show that Gymnotus omarorum and Brachyhypopomus gauderio have evolved divergent neural processes to transiently modify the CPG outputs through descending fast neurotransmitter inputs to generate communication signals. We also present two examples of electric behavioral displays in which it is possible to separately analyze the effects of neuropeptides (mid‐term modulation) and gonadal steroid hormones (long‐term modulation) upon the CPG. First, the nonbreeding territorial aggression of G. omarorum has been an advantageous model to analyze the status‐dependent modulation of the excitability of CPG neuronal components by vasotocin. Second, the seasonal and sexually dimorphic courtship signals of B. gauderio have been useful to understand the effects of sex steroids on the responses to glutamatergic inputs in the CPG. Overall, the electromotor CPG functions in a regime that safeguards the EOD waveform. However, prepacemaker influences and hormonal modulation enable an enormous versatility and allows the EOD to adapt its functional state in a species‐, sex‐, and social context‐specific manners.     

Brain androgen receptor expression correlates with seasonal changes in the behavior of a weakly electric fish,Brachyhypopomus gauderio

Seasonal breeders are superb models for understanding natural relationships between reproductive behavior and its neural bases. We investigated the cellular bases of hormone effects in a weakly pulse-type electric fish with well-defined hormone-sensitive communication signals. Brachyhypopomus gauderio males emit social electric signals (SESs) consisting of rate modulations of the electric organ discharge during the breeding season. This discharge is commanded by a medullary pacemaker nucleus (PN), composed of pacemaker and relay neurons. We analyzed the contribution of androgen receptor (AR) expression to the seasonal generation of SESs, by examining the presence of ARs in the PN in different experimental groups: breeding, non-breeding, and testosterone (T)-implanted non-breeding males. AR presence and distribution in the CNS was assessed through western blotting and immunohistochemistry using the PG-21 antibody, which was raised against the human AR. We found AR immunoreactivity, for the first time in a pulse-type Gymnotiform, in several regions throughout the brain. In particular, this is the first report to reveal the presence of AR in both pacemaker and relay neurons within the Gymnotiform PN. The AR immunoreactivity was present in breeding males and could be induced in T-implanted non-breeding males. This seasonal and T-induced AR expression in the PN suggests that androgens may play an important role in the generation of SESs by modulating intrinsic electrophysiological properties of pacemaker and relay neurons.     

Social regulation of electric signal plasticity in male Brachyhypopomus gauderio

In animal communication, the social context that elicits particular dynamic changes in the signal can provide indirect clues to signal function. Female presence should increase the expression of male signal traits relevant for mate-choice, while male presence should promote the enhancement of traits involved in male-male competition. The electric fish Brachyhypopomus gauderio produces a biphasic electric pulse for electrolocation and communication. Pulse amplitude predicts the signaler’s body size while pulse duration predicts circulating androgen levels. Males enhance pulse amplitude and duration when the numbers of males and females increase simultaneously. Here we tested the relative effects of female presence and male presence on male signal enhancement, and whether the size of the male competitor affected this enhancement. We found that male presence drives the enhancement of both pulse amplitude and second phase duration, independently of the size of the male competitor. Female presence induces the enhancement of pulse duration, but not pulse amplitude. These data suggest that males probably attend to information about a competitor’s body size coded by pulse amplitude and attend to aggressiveness coded by a competitor’s pulse duration, both potential predictors of fight outcome. Females may be primarily concerned about information on reproductive condition coded by pulse duration.     

Phenology,pollination, and breeding system of the threatened tree Caesalpinia echinata Lam. (Fabaceae), and a review of studies on the reproductive biology in the genus

Caesalpinia echinata (brazilwood) is a threatened tree endemic to the Brazilian Atlantic forest with a global importance as it is worldwide used to manufacture the most desirable bows for violins, violas, and cellos. Although there is an international initiative for its conservation, there is a lack of studies on the reproductive biology of the species, as for the genus, a fundamental understanding for the conservation of any species. In this paper, we investigated the phenology, pollination, and breeding system of C. echinata, presenting some conservation guidelines for the species, together with a review of studies on the reproductive biology in Caesalpinia s.l. The genus has a complex taxonomic history with recent attempts to reassign its limits. Pending a final resolution of the placing of some species (including C. echinata) our revision covers the traditional Caesalpinia s.l. and includes annotations indicating to which segregate genus each species is now considered to belong, as well as the appropriate combination where this has already been published. Field work was undertaken from October/2004 to December/2006 at the Tapacurá Ecological Station, northeastern Brazil. Flowering occurred mainly in the dry season and the peak of seed dispersal was at the beginning of the wet season. Anthesis is diurnal, lasting 1 day. The flowers are zygomorphic, yellow, sweet-scented, and the effective pollinators were mainly medium-sized to large bees of the genera Centris and Xylocopa, together with the introduced Apis mellifera. Nectar volume and sugar concentration averaged 2.9±1.0 μL and 29.5±9.4%, respectively. The ovary has 1–4 ovules (2.35±0.58) and the pollen/ovule ratio was 5631.2; pollen viability was high (95.9±4.8%). Natural fruit set was low (9.2%) with mature fruits averaging 1.7±0.9 seeds. Results of the controlled pollinations and analysis of pollen tube growth revealed C. echinata presents late-acting self-incompatibility. The pollination biology and breeding system of C. echinata are discussed, together with available data on its genetics and physiology, in terms of best conservation practice for this endangered species. Data on the reproductive biology of the genus are scarce, revealing the predominance of bee pollination and SI system, with the occurrence of late-acting self-incompatibility mechanisms in some species.     

Reproductive isolation between diploid and tetraploid cytotypes of Libidibia ferrea (= Caesalpinia ferrea) (Leguminosae): ecological and taxonomic implications

Polyploidy is the most common chromosomal mechanism involved in the evolution of plants. However, the emergence of polyploid individuals does not guarantee the establishment of a new lineage, and the relationship between polyploidy and reproductive biology is therefore relevant. Libidibia ferrea is a legume tree that has diploid and tetraploid populations. In this work we analyse the reproductive biology of the species to verify the degree of reproductive isolation between the two cytotypes. Observations on phenology, floral morphology, biology, and visitors, breeding system, reproductive success and reproductive isolation were made for both cytotypes in two municipalities of northeastern Brazil. Cytotypes differed for all morphometric parameters analysed, with tetraploids exhibiting higher mean values than diploids. Both cytotypes had the same effective pollinators (native bees from the genera Centris and Xylocopa, and the introduced Apis mellifera). However, since stamens of diploids and tetraploids were of different size, it is possible that spatial separation occurs when pollen of each cytotype is deposited on a bee’s body. Diploids were self-incompatible (ISI?=?0) and exhibited high fruit-set after intraploidy crossing (20?%), whereas tetraploids were self-compatible (ISI?=?0.47) and set only 3.9?% of fruits after intraploidy crossing. Both cytotypes showed low fruit- and seed-set under natural conditions, and there was no fruit-set after crosses between them. Data are discussed in relation to the establishment of polyploids, to the pattern of distribution of the species and to the taxonomic implications. The cytotypes of L. ferrea should be considered as distinct species, since they are reproductively isolated from each other.     

The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like “Cerrado” vegetation

Bignoniaceous woody species are very important ecological components of neotropical forests, but the reproductive biology of many species, such as Cybistax antisyphilitica, remains virtually unknown. Most species of Bignoniaceae are characteristically self-sterile, despite typically exhibiting normal pollen tube growth throughout the style, combined with slow rates of ovule penetration, fertilisation and endosperm initiation in selfed pistils. Uniform abortion occurs within a few days of anthesis, indicating the occurrence of late-acting self-incompatibility (LSI). However, breeding system studies have been performed in fewer than 7% of species, and other types of breeding systems (e.g., self-compatibility and apomixis) have been reported in this family. In the present study, the reproductive biology of C. antisyphilitica was investigated by field observation of flower visitors and floral events. Moreover, reproductive biology of this species was examined through experimental pollinations, analyses of pollen tube growth and ovule penetration using fluorescence microscopy, verification of pistil longevity, and a histological analysis of unpollinated vs. self-pollinated pistils. Finally, morphological aspects, quantities and germination were investigated in seeds that resulted from different pollination treatments. Natural pollination was effected by large- and medium-sized bees, and their visiting behaviour favours a high proportion of geitonogamy and no pollen limitation. Self-pollinated flowers produced no fruits, and all of the characteristic post-pollination events cited above were verified, witnessing the occurrence of LSI with post-zygotic rejection of selfed pistils in C. antisyphilitica. Although some indications of extended pistil longevity were found in selfed pistils, this feature seemed to be affected by unidentified environmental factors. The seeds were always monoembryonic and with high viability. A larger variation in the number of viable seeds was found in fruits derived from natural pollination. A low fruit set was observed after both natural and cross-pollination, and most crossed fruits underwent abortion at several points during the juvenile phase, even when protected against herbivory. The formation of surplus flowers/juvenile fruits and the apparently wasteful selfing mechanism control implied in LSI are discussed in the context of the perennial life style of tropical woody plant species.     

A population study of epigean and subterranean Potamolithus snails from southeast Brazil (Mollusca: Gastropoda: Hydrobiidae)

Population and reproductive biology of four Potamolithus species, two epigean (P. ribeirensis and Potamolithus sp. 1) and two subterranean (P. troglobius and Potamolithus sp. 2), from the Upper Ribeira Valley, southeast Brazil, were studied, from June 1996 to June 1997, using 1 m² quadrats and counting all individuals found in these quadrats. P. ribeirensis showed the highest variation in population densities (from 0 – after floods – to 467 ind.m^?2), with average ranges from 16.0 to 284.8 ind.m^?2. The densities of the two troglobitic species (average ranges for Potamolithus sp. 2 and P. troglobius, from 17.6 to 58.4 and from 0 to 61.5 ind.m^?2, respectively), higher than those of Potamolithus sp. 1 (average from 0 to 9.3 ind.m^?2), were high for cave organisms. P. ribeirensis and the two troglobitic species showed higher densities in warmer, wetter months, while Potamolithus sp. 1 showed higher densities in cooler, less rainy months. The troglobitic species were non-seasonal, since high percentages of mature females were observed throughout the year. In the epigean species, the reproductive periods showed no detectable pattern: in 1996 P. ribeirensis had a peak in winter and in the next year (1997) in spring and summer. Potamolithus sp. 1 had reproductive peaks in fall and winter.     

Genetic variation relevant for the conservation of the narrow endemic Senecio carbonensis (Asteraceae) from the southern Andes

We studied morphological variation, reproductive biology and genetic structure of Senecio carbonensis, a narrow endemic from high elevations of the southern Andes, and compared it to Senecio peteroanus, a closely related widespread congeneric species. Using ANOVAs and discriminant analysis we showed that populations of S. carbonensis were more similar to each other in their morphology, had comparatively limited reproductive capacity and presented lower plant density and more reduced plant cover than populations of S. peteroanus. Similar high genetic variation was found at the population and species level in both species, based on isozyme variation at 14 and 11 putative gene loci that were resolved in S. carbonensis and S. peteroanus, respectively. The two species were genetically distinct. However, the small genetic distance between populations of each species suggests that either they were recently founded and that genetic drift did not have time to promote divergence, or that its effects are masked by significant current gene flow. These results show that ecological and reproductive characteristics of S. carbonensis may limit its extension and abundance. In contrast, high genetic variation at the population level is probably favored by self‐incompatibility. Despite the restricted geographical distribution and low plant density of S. carbonensis populations, genetic characteristics do not seem to be limiting their long‐term persistence. This information suggests that populations of S. carbonensis are not at risk of extinction as a result of genetic factors, although it is important to study and monitor population dynamics to further assess the degree of recruitment through time.     

The different breeding strategies of penguins: A review

The 18 penguin species are exclusively and widely distributed in the Southern hemisphere, from the Equator to the Antarctic continent, and are thus submitted to various ecological constraints in their reproductive strategy. This results in a high variability in all aspects of the breeding biology of the different species. Although penguins appear primarily adapted for a marine existence, they remain dependent on land for breeding, rearing young, and moulting. Here we describe and compare the breeding cycle of all the penguin species, highlighting the characteristics of each species in terms of breeding range, population status, threats induced by environmental changes, duration of the different phases of the breeding cycle, mate fidelity, body mass, body height, egg mass and duration of egg formation. We also focus on the breeding cycle of the genus Aptenodytes, since it largely differs from the breeding cycle of most of the other penguin species.     

Tibouchina pulchra (Melastomataceae): reproductive biology of a tree species at two sites of an elevational gradient in the Atlantic rainforest in Brazil

Low-temperature environments interfere with plant reproduction by reducing the frequency of pollinators, and this may favour reproductive strategies such as self-pollination and apomixis. Tibouchina pulchra is a common tree species that occurs at high and low sites of the Brazilian Atlantic rainforest. This study focussed on the pollination biology and breeding system of this species, describing the pollinators and the reproductive success at the two sites of an elevational gradient. Observations were made to determine extent of flowering and fruiting, to identify the richness and abundance of pollinators, and to record data on the floral and reproductive biology at these two sites. Despite more dense flowering at the high site, five visits of bees (two species) were recorded during the observation time (60?h), whereas at the low site there were 948 visits (seven species) during the same period. In contrast with the low site, the flowers of the high site released and received few pollen grains on the stigma. At the high site less fruit was set with fewer seeds as a result of open pollination than at the low site; at that site, however, more seeds were obtained from cross-pollination than at the low site. Tibouchina pulchra is self-compatible; however it is not apomictic and needs pollinators for seed set at both sites. Life-history traits other than the breeding system, for example more dense flowering, advantage of greater fertility in cross-pollination, and multiple reproductive events during the lifetime of the tree may reduce inbreeding depression, increase the hybrid vigour, and balance the lack of pollinators at the high site.     

Assessing hidden species diversity in the coral Pocillopora damicornis from Eastern Australia

The incredible range of morphological plasticity present in scleractinian corals has confused the taxonomy of the group, prompting the introduction of “ecomorphs” to explain the observed correlation between local environmental conditions and phenotypic variation. Pocillopora damicornis (Linnaeus, 1758) represents one of the best known examples of eco-phenotypic variation in scleractinian corals with a variety of forms and reproductive strategies reported across its global distribution range. Here, we reconstruct genealogical relationships of P. damicornis colonies collected from thirteen locations along the East Australian coast to examine the relationship between genetic and phenotypic diversity in this species. Haplotype networks computed from two mitochondrial DNA regions (CR, ORF) indicate that the range of morphotypes observed within this taxon fall into at least five genetically distinct mitochondrial lineages. Nuclear (HSP70, ITS2) haplowebs on the other hand recover sharp genetic discontinuities among three of the morphological groups. We conclude that P. damicornis from Eastern Australia constitutes a cryptic species complex. The misinterpretation of taxonomical units within P. damicornis may well explain its perceived variation in the ecology, biology and life history across its range.