Anchors and snorkels: heterochrony, development and form in functionally constrained fossil crassatellid bivalves

Paleobiology ◽  
2016 ◽  
Vol 42 (2) ◽  
pp. 305-316 ◽  
Author(s):  
Katie S. Collins ◽  
James S. Crampton ◽  
Helen L. Neil ◽  
Euan G. C. Smith ◽  
Michael F. Gazley ◽  
...  
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Morphological Change ◽  
Predator Avoidance ◽  
Morphological Variability ◽  
Developmental Timing ◽  
Environmental Pressure ◽  
Life Habit ◽  
Infaunal Bivalve ◽  
Key Drivers

AbstractNew growth rate estimates for nine species from three genera of New Zealand Crassatellidae (Mollusca: Bivalvia), combined with existing morphometric ontogenetic descriptions, allow identification of heterochronic processes in the evolution of these genera. Both paedomorphosis (progenesis and neoteny) and peramorphosis (hypermorphosis and acceleration) have occurred within the clade. Overall, morphological variability and response to environmental pressure in this nonsiphonate group is restricted by the interplay of anatomical and life habit constraints. Stability in the substrate, predator avoidance, sluggish burrowing speed, and inability to escape by deep burial are suggested as key drivers of, or constraints on, morphological change. Two groups of shell characters are identified: heavy, armored “anchors” and elongate “snorkels,” which combine juvenile and adult traits in shells of different sizes and ages, produced by heterochronic variation in developmental timing. Anchors and snorkels both represent different “solutions” to the problems of life as a nonsiphonate, infaunal bivalve.

Growth, morphometrics and size structure of the Diadematidae sea urchin Centrostephanus rodgersii in northern New Zealand

2012 ◽  
Vol 63 (7) ◽  
pp. 624 ◽  
Author(s):  
Danilo Pecorino ◽  
Miles D. Lamare ◽  
Mike F. Barker
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Sea Urchin ◽  
Size Structure ◽  
Growth Line ◽  
Fluorescent Marker ◽  
Zealand Population ◽  
Ecological Changes ◽  
Eastern Australia ◽  
Size At Age

The sea urchin Centrostephanus rodgersii has increased its range in Eastern Australia resulting in important ecological changes. C. rodgersii may also have expanded its distribution range to northern New Zealand in the last five to six decades, although little is known about this process and of the biology of the species in New Zealand. We investigated morphometrics as well as growth using two techniques (growth line count in genital plates and tag–recapture using the fluorescent marker tetracycline). These methods allowed modelling of size at age of C. rodgersii in New Zealand, which we compared with populations recently established in Tasmania. The modelled growth rate was only slightly higher in the New Zealand population, and no differences in morphometrics were observed. The New Zealand population structure suggests that annual recruitment occurs regularly, with the population including a range of ages (3 to 10+ years).

Post-natal growth changes in the fibre cortex and medulla of the new zealand romney and N-type sheep

1959 ◽  
Vol 53 (3) ◽  
pp. 358-368 ◽  
Author(s):  
Janet P. Tibbits
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Cortical Area ◽  
Genotypic Effect ◽  
Fibre Area ◽  
Fibre Growth ◽  
Skin Biopsies ◽  
Growth Changes ◽  
Relationship Of ◽  
The Relationship

The relationship between cortical area and fibre area has been examined in the N/N, N/ +, + / +, + /nr and nr/nr genotypes of the New Zealand Romney, using skin biopsies taken at birth, 1, 3 and 16 months of age. The presence of the nr gene was shown to reduce significantly the relative cortical area. Within the genotypes there was an increase in relative cortical area with increasing age and in two-tooth ewes of N/N and N/ + there was an increase in relative cortical area in winter compared to summer.Fibre growth rates in length for primaries and for prenatal and post-natal secondaries were found for lambs between 1 and 3 months and for 16-monthold ewes. In N/N, N/+ and nr/nr primary fibre growth tended to be increased and post-natal secondary fibre growth tended to be decreased relative to + / + values.In both cortical area and fibre growth rate the greatest genotypic effect was shown by the primary fibres.Some estimates of cortical volume have been made by combining the information on cortical area and fibre growth rate and the relationship of these factors to follicle density and mean fibre area has been discussed. Finally, an indication has been given of how the associations of all these four factors might be usefully examined in some British breeds.

INFLUENCE OF BREED OF SIRE ON THE PRODUCTION OF LIGHT AND HEAVY MARKET LAMBS

1972 ◽  
Vol 52 (2) ◽  
pp. 259-266 ◽  
Author(s):  
M. H. FAHMY ◽  
C. S. BERNARD ◽  
J. P. LEMAY ◽  
M. NADEAU
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Mortality Rate ◽  
Dressing Percentage ◽  
Lambing Rate

Data were taken on 396 lambs born to crossbred ewes to compare New Zealand-type Southdown (NZS), American-type Southdown (AS), and Suffolk (SU) rams as sires of light and heavy market lambs (20 and 40 kg liveweight respectively). Ewes mated to AS rams had 7% (P > 0.05) higher lambing rate than those mated to SU or NZS rams. Preweaning mortality rate of NZS sired lambs was 3.7 (P < 0.10 > 0.05) and 11.8% (P < 0.01) lower than those by AS and SU rams, respectively. Suffolk-sired lambs were heavier at birth and 28 days. Lambs sired by AS, NZS, and SU were 88, 82, and 83 days old at 20 kg, and 187, 172, and 166 days old at 40 kg liveweight respectively. Carcass finish score and classification were higher in NZS- and AS- than in SU-sired lambs marketed as light lambs, whereas the opposite was observed in heavy lambs. Dressing percentage was not significantly affected by breed of ram, but the lambs sired by AS rams had significantly higher pelt percentage. Lambs sired by NZS rams had generally higher lean percentage. Suffolk-sired lambs had larger bones, longer cuts, and heavier organs than those by the Southdowns. Carcasses from lambs marketed as heavy were classified 1.5 grade better, scored 2.7 points higher but dressed 0.22% lower than lambs marketed as light. Males were superior to females in growth rate and produced wholesale cuts higher in lean and lower in fat percentages. Females, however, were 8.3% (P < 0.01) higher in carcass classification than males. Other factors having significant effects were age of dam, type of birth, year, and station.

Differences in Swimming Performance Among Strains of Rainbow Trout (Salmo gairdneri)

1977 ◽  
Vol 34 (2) ◽  
pp. 304-307 ◽  
Author(s):  
Allan E. Thomas ◽  
Michael J. Donahoo
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
New Zealand ◽  
Swimming Performance ◽  
Salmo Gairdneri ◽  
Swimming Ability ◽  
Fish Swimming ◽  
Fish Size ◽  
Swimming Time ◽  
Performance Profiles

Swimming performance profiles, relating fish size to swimming time, were established for three strains of rainbow trout (Salmo gairdneri). No differences were found in slope of regressions; only in level at each size of fish. Swimming performances of New Zealand and Sand Creek strains did not differ, but were superior to the Manchester strain. In stamina results from 189-day-old fish from individual matings of seven strains and various crosses, similar strains and crosses had closely matching profiles whereas profiles of unrelated groups were variable. Comparison of slowest, average, and fastest growing fish within the New Zealand strain showed that swimming ability was not related to growth rate.

Association of theADRB3gene with birth weight and growth rate to weaning in New Zealand Romney sheep

2009 ◽  
Vol 40 (2) ◽  
pp. 251-251 ◽  
Author(s):  
A. Horrell ◽  
R. H. J. Forrest ◽  
H. Zhou ◽  
Q. Fang ◽  
J. G. H. Hickford
Keyword(s):  
Growth Rate ◽  
New Zealand ◽  
Birth Weight
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