Cryptic Species: A Mismatch between Genetics and Morphology in Millepora

Millepore morphology is highly variable and shows signs of phenotypic plasticity. Two species of Millepora are present around the islands of the Bahamas: one exhibiting a strong, blade-like structure, Millepora complanata, and the other having a delicate branch-like structure, Millepora alcicornis. The phylogenetic relationship of these corals has been under considerable debate for many years. The existence of a range of intermediate growth forms exhibiting characteristics of both recognized species has led to the re-examination of this species complex. Several methods were employed to examine the taxonomic relationship including ecological abundance surveys, morphological thin-section analysis, and sequencing of rDNA internal transcribed spacer (ITS) regions. Abundance surveys showed a demarcation of growth forms by depth at two sites but an intermingling of growth forms at a third site. Morphometric analysis resulted in discrimination between M. alcicornis, M. complanata and the intermediate growth forms. However, rDNA sequence differences revealed the presence of two distinct clades, each containing members of the two currently recognized species as well as intermediate growth forms. The sequence analysis suggests the presence of two, phenotypically plastic cryptic species. Although limited in scope, our results indicate that caution should be exercised when describing species based on morphology alone and that multiple characters, including genetic information, should be used when describing species relationships

The palaeoceanography of the Leeuwin Current : implications for a future world

Long-term progressive changes of the Leeuwin Current are linked to plate and ocean basin ‘geography’ and Cenozoic global climates and palaeoceanography. Suggestions of the presence of a proto-Leeuwin Current as early as late Middle to Late Eocene times (c. 35–42 Ma) cannot be verified by the fossil record of the western margin of Australia. “Leeuwin Current style” circulation around Australia was certainly established by the early Oligocene, in response to palaeogeographic changes in the Tasman Strait. This, followed by tectonic eorganisation of the Indonesian Archipelago throughout the Miocene, provided a palaeogeographic setting, which by the Pliocene was essentially that of today. The subsequent history of the Leeuwin Current comprises climatically-induced changes operating over orbital and sub-orbital temporal scales. Specifically, the advent of Pleistocene-style climates, especially over the last 800 000 years, and their associated interglacial – glacial states provide the two end-member climate-ocean states that have characterised Leeuwin Current activity during that time. Indications of the nature of these contrasting states is provided by: (i) the Last Interglacial (c. 125 Ka) during which sea level was higher by some +4 m, and with higher sea surface temperatures (SSTs) clearly indicating a more ‘active’ Leeuwin Current; and (ii) the Last Glacial Maximum (21 Ka), during which sea level wassome 130 m lower than today, resulting in massive shelf extensions along the coast of Western Australia, ccompanied by reduced Indonesian Throughflow, lower low latitude SSTs and changes in the Western Pacific Warm Water Pool, and with these changes, possibly reduced Leeuwin Current activity. Sub-orbital scale luctuations in current strength are driven by global climate change associated with El Niño – La Niña events as well as regional climatic changes driven by volcanism. These forcing mechanisms operate at time scales well within the reach of human experience, and provide important comparative data for predicting the response of the Leeuwin Current to climate change predicted for this century. Studies of the impact of changes in the vigour of the Leeuwin Current on shallow marine communities are in their infancy. Coupling climate models with geological analogues provide important research agenda for predicting the trajectory of future changes to the Leeuwin Current and their impacts on the marine biota of coastal Western Australia

Resilience and recovery of coral reefs from large-scale disturbances: Contrasting patterns for San Salvador Island, Bahamas, and Belize

Coral cover and diversity are declining while macroalgal abundance is increasing in most Caribbean coral reef systems. Although a complex interaction of natural and anthropogenic disturbances is likely causal, the effects of a specific disturbance may vary dramatically for different reef systems. The coral reefs off the coasts of San Salvador Island, Bahamas and Belize, considered to be in relatively good condition, recently experienced near-direct hits by Hurricanes Floyd (1999) and Mitch (1998), respectively. In addition, NOAA scientists indicated that during 1998, tropical sea surface temperatures (SSTs) reached their highest levels above the normal annual maximum for this past century. With repeated monitoring of reefs off south­ central Belize and San Salvador Islan Bahamas, we have been able to document the severity of effects from these large-scale natural disturbances. Our patch reef and bank-barrier reef sites off San Salvador showed minimal damage from Hurricane Floyd, while our study sites on the forereef region off Belize were more heavily impacted by the passage of Hurricane Mitch. Although Agaricia spp. was the coral most strongly affected by the 1998 elevated SSTs on patch reefs around San Salvador Island (McGrath and Smith, 1999), we found scant evidence of bleaching of any coral colonies by January and June 2000. However, three-fold increases in partial colony mortality for this species are likely related to the bleaching stress. On the coral-reef ridges off south-central Belize, Agaricia tenuifo/ia experienced \u3e90% mortality associated with the 1998 warming event. The mound and boulder corals were also strongly affected by elevated SSTs; \u3e 50% of the colonies of Montastrea annularis complex and Diploria spp. were severely bleached. A major reef-builder, M annularis still showed widespread bleaching 9 months after the warming event, with -55% of the corals showing \u3e50% partial colony mortality. Mean partial colony mortality was 2 to 5 times higher for reef sites monitored off south­ central Belize than San Salvador. For example, a major reef builder, Acropora palmata, showed a significant decline in partial colony mortality off San Salvador, while 75% of the colonies off Belize showed dramatic mortality. M annularis experienced similar, elevated trends of colony degradation on the Belize reef; the condition of the San Salvador population remained relatively stable over the two-year period. A combination of large-scale disturbances, including two coral bleaching events (1995 and 1998) and the effects of Hurricane Mitch have thus taken a dramatic toll on the Belize reef complex. The reefs off San Salvador Island showed notable resistance and resilience to these large-scale disturbances. We hypothesize that escalating anthropogenic impacts on the Belize barrier reef have exacerbated the effects of Hurricane Mitch and elevated SSTs; thus, full recovery from these back-to-back natural disturbances may be difficult and lengthy for this reef system

Shallow-water reefs in transition: Examples from Belize and the Bahamas

The plight of coral reefs throughout the Caribbean region has been widely reported by reef scientists. A variety of causes has lead to reefal decline, particularly in shallow waters. This study compares the responses of shallow-water reefs in Belize and the Bahamas to outbreaks of white­ band disease (WBD) and traces changes on these reefs to the early 2000s. Prior to the mid-1980s, reef ridges of the Pelican Cays of Belize were constructed of luxu­ riant stands of Acropora cervicomis. As else­ where, this species suffered massive mortality in mid-1980s owing to WBD, and dead A. cervicor­ nis substrates were quickly colonized by Agaricia tenuifolia. Subsequently, A. tenuifolia on the reef ridges was severely affected by the intense El Nino-Southern Oscillation (ENSO)-related bleaching event of 1998. Our surveys showed that \u3e90% of A. tenuifolia colonies died following bleaching. More recent survey data indicate that sponges are aggressively colonizing the coral sub­ strata. In the early 1980s, Telephone Pole Reef on San Salvador Island, Bahamas, had numerous thickets of Acropora cervicomis along with large colonies of Montastraea annularis species com­ plex. By the mid-l 980s, virtually all A. cervicor­ nis colonies were dead, presumably from WBD. Following the demise of the A. cervicomis thick­ ets, an increase in Porites porites colonies quickly occurred. P. porites was opportunistic in coloniza­ tion and showed preference for A. cervicomis substrates. By the early 1990s, P. porites was a dominant coral on Telephone Pole Reef, with col­ ony sizes commonly greater than 1 min diameter. Reef surveys in 1998 and 2000 indicated signifi­ cant decline in the health of P. porites, and in early 2002 continued deterioration was noted, with virtually all larger colonies overgrown by fleshy green macroalgae and/or encrusted by coralline algae. These two examples are similar in that both shallow-water reefs are in rapid transition to domination by non-coral groups that impede set­ tlement of coral larval recruits: sponges in Belize and macro- and coralline algae in the Bahamas. Depending on how widespread similar transitions may be, the future of shallow-water coral reefs throughout the wider Caribbean is problematic. Turnover events such as these have been de­ scribed as unprecedented for coral reefs, and pa­ leontologists should examine the Cenozoic coral reef record in greater detail to explore these claims

Taphonomic evidence for Late Pleistocene transitions in coral reef community composition, San Salvador, Bahamas

Over the past 20 years, the composi­ tion of Caribbean coral reef communities has changed drastically. The ecology of modern reefs, however, has only been studied since the late 1950\u27s. Thus, only a thirty year data set on changes in coral community composi­ tion exists with which to assess the current faunal transition. The need for longer term data has been recognized by marine ecologists as essential for determining whether the cur­ rent transition is part of a long tenn cycle or itself is an unprecedented phenomenon. On Telephone Pole Reef, San Salva­ dor, Bahamas, a transition from Acropora cer­ vicornis dominance to that of Porites porites has been observed in recent years. Dead A. cervicornisa specimens found at this locality display high levels of taphonomic alteration, which may serve as a marker for prior transi­ tions of this type in other reefs. It is not known, however, if a transition of this nature occurred in the past. The fossil record provides precisely the database required for answering this ques­ tion. A detailed examination of the fossil reef at Cockburn Town, San Salvador, Bahamas, has been performed in order to evaluate whether it preserves evidence of community transitions analogous to those occurring today. Specimens of fossil corals were collected from six stratigraphic horizons and a variety of ta-phonomic were obtained. Although different styles of preservation characterize specific ho­ rizons in the fossil reef, evidence does not ex­ ist for a Pleistocene precedent for the transi­ tion currently observed offshore

Comparison of Recent Coral Life and Death Assemblages to Pleistocene Reef Communities: Implications for Rapid Faunal Replacement on Recent Reefs

Marine ecologists and paleoecologists are increasingly recognizing that the Pleistocene and Holocene fossil record of coral reefs is the exclusive database from which an assessment of the long-term responses of reef communities to environmental perturbations may be obtained. The apparent persistence of coral communities in the face of intense fluctuations in sea level and sea surface temperature during glacial and interglacial stages of Pleistocene time is in marked contrast to dramatic fluctuations in reef community structure documented by short-term monitoring studies. We compared the taxonomic structure of live and dead coral communities on a modem patch reef currently undergoing a community transition to late Pleistocene facies exposed in the CockburnTown fossil coral reef. Multidimensional scaling revealed that specific taxa and colony growth forms characterize life, death, and fossil assemblages. The recent decline of thickets of Acropora cervicorn is is represented by their abundance in the death assemblage, while Porites porites dominates the coral life assemblage. Although additional study of Pleistocene reefal facies is required, the greater similarity of the death assemblage to the fossil assemblage suggests that the present Caribbean- wide decline of A. cervicornis is without a historical preceden

Fernandez Bay, San Salvador, Bahamas: A Natural Laboratory for Assessment of the Preservation of Coral Reef Community Structure

Reprinted from: James L. Carew (ed.), Proceedings of the 8th Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Statio

Shallow-Water Coral Reefs in Transition: Examples from Belize and The Bahamas

Reprinted from: Ronald D. Lewis and Bruce C. Panuska (eds.) Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Cente

Assessment of Selected Reef Sites in Northern and South-Central Belize, Including Recovery from Bleaching and Hurricane Disturbances (Stony Corals, Algae and Fish)

The condition of coral. algal. and fish populations in fore reefs. patch reefs, and coral reef ridges was investigated at 13 sites along the northern and south-central Belize barrier reef during May 1999, documenting effects of the 1998 warming episode and Hurricane Mitch. We found high percentages of partial, or even complete, colony mortality of major reef-builders (Acropora palmata, the Montastraea annuluris species complex and Agaricia tenuifolia) that were rarely censused as recruits. A. tenuifolia, formerly a space-dominant coral in reef ridges, had incurred nearly 100% mortality after bleaching. Nearly 45% of the M. annurluris complex was still discolored (50% had been bleached in January 1999) on some south-central patch reefs where the total (recent + old) partial mortality exceeded 60% of colony surfaces. Although turf algae dominated patch reefs and coral reef ridges, macroalgae were quite prevalent representing \u3e30% cover at six sites. Parrotfish densities exceeded surgeontishes at most sites (11/13). Consistent patterns of lower partial-colony mortality of stony corals and greater fish densities and sizes near and within the Hol Chan Marine Reserve highlight the ecological benefits of protected areas for the maintenance of reef corals and attendant fish populations

Genomic analyses in Cornelia de Lange Syndrome and related diagnoses: Novel candidate genes, <scp>genotype–phenotype</scp> correlations and common mechanisms

Cornelia de Lange Syndrome (CdLS) is a rare, dominantly inherited multisystem developmental disorder characterized by highly variable manifestations of growth and developmental delays, upper limb involvement, hypertrichosis, cardiac, gastrointestinal, craniofacial, and other systemic features. Pathogenic variants in genes encoding cohesin complex structural subunits and regulatory proteins (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major pathogenic contributors to CdLS. Heterozygous or hemizygous variants in the genes encoding these five proteins have been found to be contributory to CdLS, with variants in NIPBL accounting for the majority (&gt;60%) of cases, and the only gene identified to date that results in the severe or classic form of CdLS when mutated. Pathogenic variants in cohesin genes other than NIPBL tend to result in a less severe phenotype. Causative variants in additional genes, such as ANKRD11, EP300, AFF4, TAF1, and BRD4, can cause a CdLS‐like phenotype. The common role that these genes, and others, play as critical regulators of developmental transcriptional control has led to the conditions they cause being referred to as disorders of transcriptional regulation (or “DTRs”). Here, we report the results of a comprehensive molecular analysis in a cohort of 716 probands with typical and atypical CdLS in order to delineate the genetic contribution of causative variants in cohesin complex genes as well as novel candidate genes, genotype–phenotype correlations, and the utility of genome sequencing in understanding the mutational landscape in this population