Convergent and parallel evolution in life habit of the scallops (Bivalvia: Pectinidae)

We employed a phylogenetic framework to identify patterns of life habit evolution in the marine bivalve family Pectinidae. Specifically, we examined the number of independent origins of each life habit and distinguished between convergent and parallel trajectories of life habit evolution using ancestral state estimation. We also investigated whether ancestral character states influence the frequency or type of evolutionary trajectories

Shell shape convergence masks biological diversity in gliding scallops: description of Ylistrum n. gen. (Pectinidae) from the Indo-Pacific Ocean

The scallop genus Amusium Röding, 1798 is one of few genera of Pectinidae that includes taxa capable of long-distance swimming or gliding. Membership of the genus has been defined primarily by shell shape, and it currently includes only three species: the type species A. pleuronectes (Linnaeus, 1758), A. balloti (Bernardi, 1861) and A. japonicum (Gmelin, 1791). In this study, we use molecular data and aspects of shell morphology to resolve the systematics of the genus. Phylogenetic reconstruction of Pectinidae using nuclear and mitochondrial DNA sequence from four genes supports a polyphyletic Amusium. Differences in internal ribbing pattern provide morphological evidence for the recognition of the two clades identified in our phylogenetic analyses. In contrast, quantification of shell shape through geometric morphometric methods indicates that shape is a convergent phenotype and is not informative in terms of distinguishing between the two gliding lineages. Based on these results, we describe Ylistrum, n. gen, which includes two species previously assigned to Amusium. We provide characters that separate the now monotypic Amusium from the two species, Ylistrum balloti, n. comb. and Y. japonicum, n. comb

Convergent and parallel evolution in life habit of the scallops (Bivalvia: Pectinidae)

<p>Abstract</p> <p>Background</p> <p>We employed a phylogenetic framework to identify patterns of life habit evolution in the marine bivalve family Pectinidae. Specifically, we examined the number of independent origins of each life habit and distinguished between convergent and parallel trajectories of life habit evolution using ancestral state estimation. We also investigated whether ancestral character states influence the frequency or type of evolutionary trajectories.</p> <p>Results</p> <p>We determined that temporary attachment to substrata by byssal threads is the most likely ancestral condition for the Pectinidae, with subsequent transitions to the five remaining habit types. Nearly all transitions between life habit classes were repeated in our phylogeny and the majority of these transitions were the result of parallel evolution from byssate ancestors. Convergent evolution also occurred within the Pectinidae and produced two additional gliding clades and two recessing lineages. Furthermore, our analysis indicates that byssal attaching gave rise to significantly more of the transitions than any other life habit and that the cementing and nestling classes are only represented as evolutionary outcomes in our phylogeny, never as progenitor states.</p> <p>Conclusions</p> <p>Collectively, our results illustrate that both convergence and parallelism generated repeated life habit states in the scallops. Bias in the types of habit transitions observed may indicate constraints due to physical or ontogenetic limitations of particular phenotypes.</p

Systematics of the Australasian Lymnaeidae

The Lymnaeidae Rafinesque, 1815 are one of the most widespread groups of freshwater snails, however, they are characterised by a long and confused systematic history largely due to problems associated with shell plasticity. Recent molecular studies that have utilised DNA sequences have failed to adequately represent the Australasian lymnaeids. The aim of this study was to understand the systematics of the Australasian Lymnaeidae, using 16S and ITS-2 sequences in tandem with a anatomical and shell studies. The native Australian and New Zealand lymnaeids are currently attributed to Austropeplea Cotton, 1942 and Kutikina Ponder and Waterhouse 1997, which are thought to be represented by three and one species, respectively. Results of this study indicate there are 5 distinct species across three genera. Phylogenetic analyses of the A. tomentosa (Pfeiffer, 1855) complex recovered two distinct species, A. tomentosa in New Zealand and A. huonensis (Tenison-Woods, 1876) in southern Australia. There was however incongruence between the anatomical and molecular phylogenies. Kutikina hispida was suggested to be closely related to the A. tomentosa complex, however, molecular phylogenies genes resolved K. hispida as sister to A. huonensis, with A. tomentosa being resolved as sister to the A. huonensis + Kutikina clade. Kutikina was therefore synonymised into Austropeplea based on the molecular phylogenies. Based on molecular and anatomical phylogenies, the more northern complex, A. lessoni (Deshayes, 1830) was more appropriately placed in the Peplimnea (Iredale, 1943), and was found to be represented by two distinct taxa, P. lessoni and P. affinis (Küster, 1862). Phylogenetic analysis of 16S, ITS-2 and anatomical characters recovered A. viridis (Quoy and Gaimard, 1832) as relatively divergent from other members of Austropeplea. Therefore, A. viridis was placed into Viridigalba Kruglov and Starobogatov, 1985. Using 16S sequences and anatomical characters, a phylogeny of the Lymnaeidae was produced. The Australasian lymnaeids represented one of the most derived groups within the family in both the 16S and anatomical phylogenies. The North American and European lymnaeids were resolved at the base of the lymnaeid phylogeny, suggesting that these taxa represent the older groups within the family. Phylogenies based on molecular sequences suggest that the Austropeplea lessoni complex is more closely related to lymnaeids from South East Asia than to other Australian lymnaeids. Furthermore, based on molecular and anatomical phylogenies, A. viridis is suggested as sister to the A. tomentosa complex. Therefore it is highly likely the A. lessoni complex and A. tomentosa complex have separate derivations. The monophyly of Radix Montfort, 1810 remains however unresolved. Two theories of biogeography of the Australasian Lymnaeidae have been recently proposed and were examined in light of the new phylogeny. While it seems certain that the Austropeplea lessoni complex had a South East Asian origin, the origin of the A. tomentosa complex is still unclear. The close relationship of the A. tomentosa complex with Asian A. viridis plus the derived position of the group in the family, suggest a second invasion of Australia by lymnaeids from South East Asia. However, the basal position of the New Zealand A. tomentosa would suggest the group occurred here first and moved into Australia, thus suggesting a Gondwanan radiation of the A. tomentosa complex. The discovery of a lymnaeid fossil in Antarctica lends further weight to this theory

Science, engineering, and maths expo in Mudgee

St Matthews Catholic School held a Science, Maths and Engineering Careers Expo which was pitched at our Year 8, 9 and 10 students, and aimed to introduce our students to the wide range of career options that rely on Science and Maths. It was also pitched at this level as by Year 10 students are beginning to think about their Stage 6 course selection. The careers expo drew upon the expertise of the St Matthew's school community and the wider Mudgee community. Around 35 different professionals from the local Mudgee community attended; the majority of these professionals are parents in our school community, but we were also fortunate enough to have a couple of St Matt's alumni, Ben Fitzsimmons, an engineer for HumeCoal, and Jason Streat, a sports analyst for the St George Dragons

Hands-on science mentoring beneficial for rural students

In their recent Australian Journal of Education paper, An Australian-based authentic science research programme transforms the 21st century learning of rural high school students, Louise Puslednik (Science Coordinator at St Matthews Catholic School in Mudgee, New South Wales) and Professor Patrick C Brennan (from the University of Sydney) assess the short-term impact of a hands-on mentor program on the science skills of students in rural New South Wales. Here, Puslednik shares details of the program – which required Year 10 students to collect first-hand data leading to scientific publications – and the benefits for participating students

The architecture of insects - Intersection of art and science

[Extract] The aim of this work was to provide students with the latitude to think, discover, and make connections through an integrated art and science unit using insects as the key focus

An Australian-based authentic science research programme transforms the 21st century learning of rural high school students

Authentic student-led inquiry and exposure to scientific research impact students’ science career choices. Given Australian students decline in STEM skills, knowledge of whether such programmes impact student learning is critical. This research examined the short-term impact of an authentic, hands-on research mentor programme on rural student’s science skills. Nine Year 10 students participated in a science academic research programme leading to scientific publications and students collecting of first-hand data from international experiments on a major world-wide health issue. The NSW Department of Education Year 10 VALID assessment scores of this intervention group were compared to a control group. Intervention students had significantly higher overall scores as well as significantly higher scores in 21st century skills. These results were supported by student’s self-assessment of their learning growth. Our study suggests authentic science research mentor programmes are pedagogically advantageous for Year 10 high achieving rural students. Educators’ willingness to embrace these innovative approaches has the potential to produce the next generation of scientists

Convergent and parallel evolution in life habit of the scallops (Bivalvia: Pectinidae)

Background: We employed a phylogenetic framework to identify patterns of life habit evolution in the marine bivalve family Pectinidae. Specifically, we examined the number of independent origins of each life habit and distinguished between convergent and parallel trajectories of life habit evolution using ancestral state estimation. We also investigated whether ancestral character states influence the frequency or type of evolutionary trajectories. Results: We determined that temporary attachment to substrata by byssal threads is the most likely ancestral condition for the Pectinidae, with subsequent transitions to the five remaining habit types. Nearly all transitions between life habit classes were repeated in our phylogeny and the majority of these transitions were the result of parallel evolution from byssate ancestors. Convergent evolution also occurred within the Pectinidae and produced two additional gliding clades and two recessing lineages. Furthermore, our analysis indicates that byssal attaching gave rise to significantly more of the transitions than any other life habit and that the cementing and nestling classes are only represented as evolutionary outcomes in our phylogeny, never as progenitor states. Conclusions: Collectively, our results illustrate that both convergence and parallelism generated repeated life habit states in the scallops. Bias in the types of habit transitions observed may indicate constraints due to physical or ontogenetic limitations of particular phenotypes.This article is from BMC Evolutionary Biology 11 (2011): 164, doi:10.1186/1471-2148-11-164. Posted with permission.</p