A comparative study of seed morphology in relation to desiccation tolerance and other physiological responses in 71 Eastern Australian rainforest species

Seed characteristics were measured in 71 Eastern Australian rainforest species representing 30 families. Sensitivity to desiccation to low moisture contents (< 10%) occurred in 42% of species. We estimate, based on findings from 100 species from this present study and previously published reports, that 49% of Eastern Australian rainforest species have non‐orthodox seeds. Germination level and time to 50% germination were not significantly different between desiccation sensitive (DS) and desiccation tolerant (DT) seeds. The estimation of seed desiccation sensitivity based on predictors is an important tool underpinning ex situ conservation efforts. Seed characteristics differed significantly between DS and DT seeds; that is, DS seeds had: (i) larger fruits (19 949 mg vs 8322 mg); (ii) larger seeds (1663 mg vs 202 mg); (iii) higher seed moisture contents (49.7% vs 35.5% fresh weight); (iv) lower oil content (7.3% vs 24.8% yield); and (v) less investment in seed coats (0.19 vs 0.48 seed coat ratio). Only 25% of DS seeded species had oily seeds compared with 87% of DT seeded species. Most green embryos were DS. Seed coat ratio was the best predictor of seed DS (80% correctly predicted). Seed moisture content at maturity was also related to germination time. Mean seed size was correlated (?0.657, P = 0.01) with mean seed oil content in 46 species. Further research on seed storage physiology of possible oily and/or DS seeded species is crucial to ensure future long‐term security of this biodiversity, particularly for species currently threatened in situ and/or of socioeconomic importance in Eastern Australian rainforests.     

Phospholipase Dα1‐mediated phosphatidic acid change is a key determinant of desiccation‐induced viability loss in seeds

High sensitivity of seeds to water loss is a widespread phenomenon in the world's plant species. The molecular basis of this trait is poorly understood but thought to be associated with critical changes in membrane function. We profiled membrane lipids of seeds in eight species with varying levels of desiccation tolerance and found a close association between reducing seed viability and increasing phosphatidic acid (PA). We applied hydration–dehydration cycles to Arabidopsis seeds, which are normally desiccation tolerant, to mimic the onset of desiccation sensitivity with progression towards germination and examined the role of phospholipase D (PLD) in desiccation stress‐induced production of PA. We found that PLDα1 became more abundant and migrated from the cytosol to the membrane during desiccation, whereas PLDδ did not change, and that all desiccation‐induced PA was derived from PLDα1 hydrolysis. When PLDα1 was suppressed, the germination level after each hydration–dehydration cycle improved significantly. We further demonstrated that PLDα1‐mediated PA formation modulates desiccation sensitivity as applying its inhibitor improved seed desiccation tolerance and its suppression in protoplasts enhanced survival under dehydration. The insights provided by comparative lipidomics enable us to propose a new membrane‐based model for seed desiccation stress and survival.     

The effect of light and seed mass on seed germination of common herbaceous species from the eastern Qinghai‐Tibet Plateau

Smaller seeds might encounter more severe selective pressure than larger ones because they have fewer food reserves and are more easily buried; thus, seed mass can be considered to be directly related to the effect of light on germination. To investigate the effect of light on seed germination and associated seed mass variation within a whole plant community, we compiled germination data for common herbaceous species from an alpine meadow on the eastern Qinghai‐Tibet plateau. The results showed the following. (i) Light had a general positive effect on seed germination. Under light, the proportion of species with lower germinability was decreased, mean germination percentage was increased by 20% and the speed of germination was doubled. (ii) Irrespective of light environment, species with medium‐sized seeds (seed mass ranging from 0.11 to 0.5 mg) had higher germination percentage and speed when compared with species within the largest seed mass group. (iii) The germination of smaller‐seeded species was more dependent on light stimulation than larger‐seeded ones. In darkness, the species within the smallest seed mass group had the lowest percentage and speed of germination; however, under light, the species within the largest seed mass group had the lowest percentage and speed of germination. Our results suggested that the germination characteristics and especially seeds’ response to light among species in the alpine meadow might be an adaptation to natural selective pressure.     

Can seed characteristics or species distribution be used to predict the stratification requirements of herbs in the Australian Alps?

The germination requirements of 19 herbs in the Australian Alps were investigated to determine which species may be sensitive to predicted climate changes. Seeds were subjected to factorial treatments of cold stratification for 0, 4, 8 and 12 weeks, followed by incubation at constant temperatures of 10, 15, 20 and 25 °C and alternating temperatures of 20/5 and 20/10 °C. Germination responses were used to identify stratification‐dependent species, to classify dormancy and to determine optimum conditions for laboratory germination. Ordinal logistic regression was used to determine whether the duration of stratification required for ≥ 50% germination could be predicted by seed weight, seed length, embryo : seed ratio or species distribution (latitudinal range, altitudinal range and maximum altitude). The Kruskal–Wallis test was used to determine any significant differences in stratification requirement between endospermic and non‐endospermic seeds. Species varied considerably in their response to the treatment combinations, and therefore their dormancy class. No significant predictors of stratification requirement were identified by ordinal logistic regression (P > 0.9); however, there was a significant difference in stratification requirement between endospermic and non‐endospermic seeds (P = 0.003). Species with non‐endospermic seeds did not require any stratification to germinate well over a range of temperatures, and appear most likely to remain stable or expand in range in response to climate warming. Conversely, the need for ≥ 8 weeks of cold stratification was associated with the presence of endosperm and either a restricted distribution or upland ecotypes of widely distributed species. Alpine species with endospermic seed and a restricted distribution are most likely to contract in range under climate change and would be appropriate to prioritize for ex situ conservation. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 187–204.     

Seed survival of the tropical tree Cryptocarya aschersoniana (Lauraceae): Consequences of habitat disturbance

Seed survival in soil could be strongly influenced by habitat characteristics, but little is known about the behaviour of seeds sensitive to desiccation in seed banks installed in natural or disturbed habitats. Cryptocarya aschersoniana seeds disperse at the end of the rainy season but do not germinate immediately; thus, they may form seed banks in soil. This study evaluated the behaviour of C. aschersoniana seed banks induced in the natural environment of the species and in a disturbed area. Recently harvested C. aschersoniana germination units were characterized according to their water content, germination and viability. In 2011 and 2012, seed banks were established by burying samples of seeds in the understory of a semi‐deciduous forest. In 2012, samples were also buried in a disturbed area. The seed banks were sampled at certain time intervals, and the samples were characterized as described above. Precipitation and air temperature data were collected. As a result, seeds in the seed bank established in the natural environment form a transient seed bank and showed the same behaviour in both years studied. A germination peak was observed starting 210 days after burial (coinciding with the onset of the rainy season) and reached germination percentages higher than 80% at the end of the experiment for both years. Seed mortality did not exceeded 28% in the natural environment. However, in the disturbed environment, the seeds lost their viability more rapidly, with 90% of the seeds becoming unviable 240 days after burial. Germinated seeds in the disturbed environment (maximum 21%) were not able to establish seedlings. These results underscore the importance of maintaining a natural, undisturbed forest for the conservation of this species.     

种子顽拗性的形成机理及其保存技术

根据种子的脱水行为将种子分为正常性种子、顽拗性种子和中间性种子。顽拗性种子在发育的末期不经历成熟脱水．脱落时有相对高的含水量,并且对低温和脱水干燥非常敏感。在自然界,顽拗性种子存在一个连续群,即低度、中度和高度顽拗性种子,其差异在于对脱水伤害的敏感程度。影响种子顽拗性的因素,既有种子本身的生理生化物质基础,也有种子在母株上发育过程中所经受的外界环境的影响。目前,对种子脱水耐性的分子机制及其保存技术研究得较多。本文综述了有关顽拗性种子研究的近期进展。     

The effect of seed mass and gap size on seed fate of tropical rain forest tree species in guyana

Abstract: For eleven tree species, differing in seed mass, germination success (emergence success for two small-seeded species) and the causes of failure to germinate were studied in the forest understorey and in logging gaps in the tropical rain forests of Guyana. In the forest understorey, germination success increased with seed mass. However, as gap size increased the difference between smaller and larger seeded species diminished because germination success of smaller-seeded species increased slightly, while that of larger-seeded species decreased dramatically. The negative effect of gap size on germination success of larger-seeded species was caused by an increased risk of desiccation with gap size, which was a far more important seed mortality agent for larger than for smaller-seeded species. Generally, seeds of smaller-seeded species suffered more from insect predation and were removed at higher rates than larger-seeded species. On the other hand, larger-seeded species were eaten more by mammals than smaller-seeded species. It is concluded that logging can result in shifts in the species composition in the tropical rain forests of Guyana which are dominated by species with large seeds, since germination success of larger-seeded species is dramatically reduced in large logging gaps.     

西双版纳热带季节雨林四种珍稀濒危树种种子萌发对脱水和光的响应

绒毛番龙眼(Pometia tomentosa)、琴叶风吹楠(Horsfieldia pandurifolia)、箭毒木(Antiaris toxicaria)和思茅木姜子(Litseapierrei var. szemois)是西双版纳热带季节雨林乔木层的优势树种,也属于珍稀濒危物种。实验研究了4个树种的种子在经过不同脱水水平、人工遮荫条件下的不同光照水平以及热带季节雨林之林下和林窗的萌发特性。结果显示:脱水对于种子萌发特征具有显著影响,绒毛番龙眼和琴叶风吹楠经48h的连续脱水后丧失了萌发能力;箭毒木和思茅木姜子具较强的脱水耐性,经96h的连续脱水后仍具有较高的种子含水量,且种子萌发率分别为15%和33%。干旱季散布的种子比雨季散布的种子具有更强的脱水耐性。遮荫及森林种子萌发试验中,除绒毛番龙眼外,其它3个树种的种子萌发率以及平均萌发周期在不同光水平或生境下差异显著。琴叶风吹楠和思茅木姜子在30%的光照以及林窗中心的萌发率要显著低于低光处理(10%和3.5%光照)和林下,而箭毒木在30%和10%光水平以及林窗中心获得较高萌发率。雨季传播的具有干燥敏感性的种子,可以减少种子由于干燥而引起的死亡。试验结果可以为4种珍稀濒危植物的保护和人工繁育提供一定理论依据。     

A role for fruit structure in seed survival and germination of Swartzia langsdorffii Raddi beyond dispersal

• Diaspore structure has been hypothesised to play a role in seed viability and/or germination of recalcitrant seeds, especially for Swartzia langsdorffii. Thus, this work aims to (i) investigate the in situ contribution of pericarp and aril on seed viability and germination, and (ii) identify morphoanatomical traits of S. langsdorffii diaspores that allow its desiccation‐sensitive seeds to remain viable.
• The role of the pericarp and aril in seed survival and germination was investigated by placing the whole fruit, whole seeds (arillate seed) and bare seeds (without aril) in soil in the forest understorey, assessing germination, emergence, dead, firm and predated seeds, and water content of pericarps, arils and seeds. Correlation analysis was performed between environmental variables and physiological parameters. Histochemical features of diaspores were also investigated.
• Pericarp water content fell after several months, while the aril maintained its water content. Seeds did not lose water even without the presence of the pericarp and aril. However, presence of the pericarp promoted seed water content, viability and germination long after dispersal. The embryo had a thickened outer periclinal cell wall.
• Pericarp and aril are not essential to prevent water loss in seeds, but do help to retain seed moisture, favouring viability maintenance and promoting germination during the rainy season. Morphoanatomical features of seeds are suggested as main factors that reduce water loss. Survival of these desiccation‐sensitive seeds upon dispersal during the dry season appears to be facilitated by multiple diaspore features that prevent viability loss.

     

Small mammal controls on the climate‐driven range shift of woody plant species

Climate change is resulting in shifts in species’ ranges as species inhabit new climatically suitable areas. A key factor affecting range‐shifts is the interaction with predators. Small mammals, being primary seed predators and dispersers in forest ecosystems, may play a major role in determining which plant species will successfully expand and the rate at which range‐shifts will occur. Plants dispersing seeds beyond the species’ current range limits will encounter seed predators to which these seeds are novel; however, empirical studies of seed predator–novel seed interactions are lacking. The aims of our study were to: 1) quantify seed selection by small mammals presented with ‘novel’ seeds; 2) quantify the post‐selection fate of ‘novel’ seeds; and 3) identify seed traits that affect seed selection and post‐selection seed fate. We designed a field experiment exposing small mammal communities to novel seeds produced by plants expected to shift their ranges in response to climate change. We matched novel seeds with reference ‘familiar’ seeds and studied key steps defining interactions between small mammals and novel seeds. We found that the probability of selection of a novel seed varied among species and was, at times, higher than the selection probability of familiar seeds. Key traits that affected seed selection and the distance a seed was dispersed for caching were shell hardness and seed mass. We also found that 33% of dispersed seeds were cached in optimal germination sites (e.g. within fallen logs and buried under the leaf litter mat). Through seed emergence trials we found that emergence was higher for larger seeds, suggesting that the role of small mammals may be modulated by emergence rates. Our results suggest that the interaction between small mammals and novel seeds may have cascading effects on climate‐induced plant range shifts and community composition.     

Prediction of desiccation sensitivity in seeds of woody species: a probabilistic model based on two seed traits and 104 species

BACKGROUND AND AIMS: Seed desiccation sensitivity limits the ex situ conservation of up to 47 % of plant species, dependent on habitat. Whilst desirable, empirically determining desiccation tolerance levels in seeds of all species is unrealistic. A probabilistic model for the rapid identification of woody species at high risk of displaying seed desiccation sensitivity is presented. METHODS: The model was developed using binary logistic regression on seed trait data [seed mass, moisture content, seed coat ratio (SCR) and rainfall in the month of seed dispersal] for 104 species from 37 families from a semi-deciduous tropical forest in Panamá. KEY RESULTS: For the Panamanian species, only seed mass and SCR were significantly related to the response to desiccation, with the desiccation-sensitive seeds being large and having a relatively low SCR (i.e. thin 'seed' coats). Application of this model to a further 38 species, of known seed storage behaviour, from two additional continents and differing vegetation types (dryland Africa and temperate Europe) correctly predicted the response to desiccation in all cases, and resolved conflicting published data for two species (Acer pseudoplatanus and Azadirachta indica). CONCLUSIONS: This model may have application as a decision-making tool in the handling of species of unknown seed storage behaviour in species from three disparate habitats.     

青藏高原东缘61种常见木本植物种子萌发特性及其与生活史的关联

为了评价亚高山地带木本植物种子萌发对策及其与生活史关联, 该文对青藏高原东缘61种常见木本植物的种子萌发特征以及种子萌发与种子大小、扩散方式、海拔及生境的关系进行了调查分析。结果表明: 1) 61种植物的种子萌发率呈现偏斜、双峰分布。6种植物(9.8%)的种子萌发率大于80%, 13种(21.3%)的萌发率在60%~80%之间, 9种(14.8%)的萌发率在40%~60%之间, 8种(13.1%)的萌发率在20%~40%之间, 25种(41%)的萌发率小于20%, 其中8种植物的种子萌发率为零, 显示了该生境中木本植物的种子以休眠、低萌发率或连续稳定的萌发对策占优势, 以避免不利的环境因素。2)种子扩散方式是决定61种木本植物种间萌发率变异(R² = 24.1%, p < 0.001) 和萌发开始时间变异(R ²= 21.3%, p < 0.01) 的主要因素; 种子大小、母体植株的海拔和生境对种子萌发率和萌发开始时间几乎没有影响(p > 0.05); 风扩散的种子比脊椎动物扩散和无助扩散的种子有更高的萌发率(F = 9.219, p < 0.001) 和较早的萌发开始时间(F = 6.772, p < 0.01)。说明植物生活史特征如种子萌发与扩散方式之间存在固有而紧密的联系, 扩散能力强的种子(如风扩散)由于能散布到较远而空旷的生境, 可能避免了各种有害因素或个体竞争, 因而种子以较强的萌发能力进行拓殖; 扩散能力弱的种子(如无助扩散)由于其散布距离较近, 种子以休眠或降低萌发的方式来避免个体或同胞竞争以及各种有害因素, 以获得最大的生态利益并确保物种延续。     

木波罗种子脱水敏感性与膜脂过氧化的研究

刚采收的木波罗种子含水量为５８．６％。随着含水量下降,种子的发芽率和发芽指数迅速下降,种子对脱水非常敏感,是典型的顽拗性种。自然脱水时,种子胚轴和子叶中超氧物歧化酶的活性先上升,然后下降,丙二醛和脂质氢过氧化物的含量显著增加。其脱水敏感性的原因可能是当种子脱水时,植物酶ＳＯＤ的活性下降,膜脂过氧化作用加强,从而使膜的结构和功能受到破坏,种子生活力丧失。     

Seed banking of terrestrial orchids: evaluation of seed quality in Anacamptis following 4‐year dry storage

• Good‐quality dry seeds of some orchids have the potential to survive for decades under conventional seed bank conditions, but further research is needed to fill existing gaps in knowledge regarding seed behaviour under long‐term dry storage. The objectives of this study were to evaluate germination ability on two asymbiotic culture media with different nitrogen source; to assess seed desiccation tolerance needed for the storage at sub‐zero temperatures; and to study the effects of dry storage at low temperature.
• Asymbiotic seed germination tests of four Anacamptis species were carried out to evaluate the effects of different culture media, dehydration and dry storage on germination ability. Viability of 4‐year‐stored seeds was assessed by means of the tetrazolium test.
• Generalised linear model (GLM) analysis detected significant effects (P < 0.01) of the species, medium and storage time on total germination, while dehydration did not significantly affect it. Except for A. palustris, germination percentage was minimum after 1‐month storage and increased with longer storage periods. Tetrazolium viability tests detected high percentages of viable seed (>90%) following 4‐year storage in three out of four species.
• Seeds of the four Anacamptis species proved to be desiccation tolerant and have orthodox storage behaviour. The consequence of these findings is of interest to practical conservation approaches for orchids in seed‐banking. The results highlight the importance of multiple assessments of seed quality, both viability and germination, to understand seed storage behaviour.

     

Desiccation,Moisture Content and Germination of Zostera marina L. Seed

Zostera marina is the only seagrass species whose seeds have been successfully used in large‐scale restoration. Although progress has been made in refining Z. marina restoration protocols, additional information on Z. marina seed physiology is necessary as the science of seagrass restoration evolves. We tested the germination rates of Z. marina seeds under different relative humidities and temperatures for different periods of time. Z. marina seed moisture content (MC) and germination rates were also tested when seeds were exposed to a temperature of 25°C and relative humidity of 50%. Z. marina seeds suffered higher mortality when exposed to lower relative humidity and higher temperature for longer period of exposure time. A significant negative correlation was detected between seed germination rate and MC. Z. marina seeds are sensitive to desiccation exposure and long periods of exposure to air should be prevented to minimize seed mortality when seeds are used in restoration projects.     

黄皮种子脱水敏感性与脂质过氧化作用

黄皮种子自然脱水时,种子的发芽率和发芽指数迅速下降;种子浸泡液的电导率和可溶性物质的量大大增加;线粒体膜和质膜ATPase的活性下降;种子中SOD活性先上升,然后下降;脂质过氧化产物MDA和脂质氢过氧化物的量大大增加。DDC、MDA和Fe2 促进脂质过氧化作用,降低种子生活力;ASA和甘露醇对脂质过氧化有抑制作用,提高种子生活力。     

Different plant provenance same seed tolerance to abiotic stress: implications for <Emphasis Type="Italic">ex situ</Emphasis> germplasm conservation of a widely distributed coastal dune grass (<Emphasis Type="Italic">Uniola paniculata</Emphasis> L.)

Preservation of genetic diversity within germplasm repositories represents an important tool for plant conservation. However, seeds must tolerate extreme levels of post-harvest desiccation and cold to realize benefits of ex situ storage. Factors including local climate and habitat impact expression of desiccation and freezing tolerance especially for widely distributed species. Our aim here was to understand the influence of a latitudinal gradient on seed desiccation and cryo-freezing tolerance. We sampled mature U. paniculata seeds from two geographically and genetically distinct populations then examined seed-water relations and germination following desiccation via equilibrium drying assays (0.5 to 91% RH; ?797 to ?12.9 MPa). Germination ability after drying and subsequent cryo-freezing treatments (?196?°C, 1 to 1440 min) was also evaluated. Seeds of both populations displayed similar reverse sigmoid moisture sorption isotherms characteristic of desiccation tolerant tissues. Furthermore, initial seed water potential (?63 and ?90 MPa) was considerably lower than the lethal limit (?20 MPa) identified for desiccation sensitive tissues. Final germination (range 58–93%) and temporal patterns differed significantly between populations following desiccation and cryo-freezing stress, but these germination responses were similar to initial germination. A higher proportion of non-germinated, yet viable seeds remained for the northern compared to southern population. Location does influence germination response, but differential germination is related to seed dormancy rather than desiccation or cryo-freezing sensitivity. Ex situ conservation of U. paniculata is therefore feasible across the latitudinal gradient studied here.     

Comparative effects of desiccation,heat shock and high temperatures on seed germination of savanna and forest tree species

Although forest and savanna biomes predominate in tropics regions, the factors that control their distribution remain unclear. South American savannas occur in regions that are considered warm and humid enough to support forests, indicating that agents other than climate determine the occurrence of one or the other physiognomy. Herbivory, fire and water deficit have been considered environmental filters that limit the forest species encroachment in savanna physiognomies, but the effects of these filters on the capability of these species to recruit from seeds remain poorly understood. In this study we investigated how stress factors characteristic of savanna environments, such as soil desiccation, heat shocks and high temperatures affect the survival and germination of seeds from savanna and forest tree species. We found that desiccation (to 5%) reduced the germination percentage of forest seeds, but had no effect on the germination of savanna seeds. Forest seeds were less tolerant to heat shocks of 140°C and 200°C, and showed lower germination percentage at temperatures of 35 and 40°C, when compared with savanna seeds. Savanna seeds presented longer germination times and higher germination variance than forest seeds, indicating a risk‐spreading germination strategy among savanna species. The low tolerance of forest seeds to desiccation, heat shock and high temperatures may explain the low recruitment of forest trees into savanna physiognomies. Climate change models predict lower soil moisture, higher temperatures and higher fires frequency for South America biomes. Our results suggest that savanna species are likely to be more capable of withstanding the effects of these changes than forest species.     

Seed traits and germination behaviour of four Sardinian populations of Helichrysum microphyllum subsp. tyrrhenicum (Asteraceae) along an altitudinal gradient

• Helichrysum microphyllum subsp. tyrrhenicum (Asteraceae) is an endemic taxon of Sardinia and Corsica, where it grows at different altitudes. The objective of this study was to investigate the seed traits and germination behaviour of four Sardinian populations of this taxon located at different altitudes.
• Seed traits were evaluated, and germination tests were carried out by incubating seeds at a range of constant (5–30 °C) and alternating (25/10 °C) temperatures. The dry after‐ripening (DAR) pre‐treatment was also applied by storing seed in dry conditions for 3 months at 25 °C. Seed traits and germination behaviour data were statistically analysed to identify if there was a correlation with altitude.
• Differences in seed size, area and mass among populations were recorded, however, no relationship was found with altitude. High germination percentages were obtained in all populations, both in untreated and DAR seeds, and were positively affected by alternating temperatures. The final germination percentage and time required to reach 50% final germination (T₅₀) showed no relationship with altitude.
• The differences in seed traits and germination detected among the studied populations of H. microphyllum subsp. tyrrhenicum were not correlated with altitude. This study provides new and important knowledge for this taxon. H. microphyllum subsp. tyrrhenicum is characterised by high germination percentages and low T₅₀ values and does not seem to require any dormancy‐breaking treatment. This species represents a high‐potential native plant species that should be considered within environmental management plans.

     

Seed development in the rare cold desert sand dune shrub Eremosparton songoricum and a comparison with other papilionoid legumes

No study has yet been carried out on seed development in a cold desert sand dune papilionoid legume. Thus, our primary aims were to (i) monitor seed development in the cold desert sand dune species Eremosparton songoricum from the time of pollination to seed maturity, and (ii) compare seed development in this species with that in other species of papilionoid legumes. Fruit and seed size, mass and seed moisture content, and seed imbibition, germination, desiccation tolerance and water retention during development (pollination to seed maturity) were monitored in the papilionaceous shrub E. songoricum in the Gurbantunggut Desert of northwest China. The duration of seed development was 40 days. Seeds reached physiological maturity 28 days after pollination (DAP), at which time 58% of them germinated and they had developed desiccation tolerance. Seeds became impermeable 36–40 DAP, when their moisture content was about 10%. The final stage of maturation drying occurred via loss of water through the hilum. The developmental stages and their timing (DAP) in seeds of E. songoricum are generally similar to those reported for other papilionaceous legumes with a water‐impermeable seed coat (physical dormancy). In general, the developmental features of seeds with water‐impermeable coats at maturity do not appear to be specific to habitat or phylogeny.