The island rule and its application to multiple plant traits

10.26686/wgtn.17136800 ◽

2021 ◽

Author(s):

◽

Annemieke Hendriks

Keyword(s):

Plant Traits ◽

Leaf Size ◽

Small Islands ◽

Small Species ◽

Island Rule ◽

Petiole Length ◽

Island Endemics ◽

Species Pairs ◽

Size Diversity ◽

Plant Stature

The Island Rule refers to a continuum of body size changes where large mainland species evolve to become smaller and small species evolve to become larger on islands. Previous work focuses almost solely on animals, with virtually no previous tests of its predictions on plants. I tested for (1) reduced floral size diversity on islands, a logical corollary of the island rule and (2) evidence of the Island Rule in plant stature, leaf size and petiole length. Endemic island plants originated from small islands surrounding New Zealand; Antipodes, Auckland, Bounty, Campbell, Chatham, Kermadec, Lord Howe, Macquarie, Norfolk, Snares, Stewart and the Three Kings. I compared the morphology of 65 island endemics and their closest ‘mainland’ relative. Species pairs were identified. Differences between archipelagos located at various latitudes were also assessed. Floral sizes were reduced on islands relative to the ‘mainland’, consistent with predictions of the Island Rule. Plant stature, leaf size and petiole length conformed to the Island Rule, with smaller plants increasing in size, and larger plants decreasing in size. Results indicate that the conceptual umbrella of the Island Rule can be expanded to plants, accelerating understanding of how plant traits evolve on isolated islands.

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Repeated patterns in the evolution of size in island plants

10.26686/wgtn.17151437 ◽

2021 ◽

Author(s):

◽

Matthew Biddick

Keyword(s):

Functional Traits ◽

Large Scale ◽

Plant Traits ◽

Leaf Size ◽

Plant Functional Traits ◽

Common Element ◽

Island Rule ◽

Island Populations ◽

Stem Size ◽

Island Evolution

For reasons not fully understood, animals often evolve predictably on islands. For example, radiations of large, flightless birds are a common element of many island biotas. However, our understanding of how plants evolve on islands is comparatively poor. Further, an investigation into the evolution of island plants could help resolve unanswered questions about island animals. This thesis investigates insular size changes in a range of plant functional traits. First (Chapter 2), I explored size changes in 9 species of vines that have colonized islands from the New Zealand and Australian mainland. I asked whether leaf–stem allometry prohibits leaves and stems from evolving independently from one another. Island populations consistently produced larger leaves than did mainland populations. Moreover, changes in leaf size were not associated with concomitant changes in stem size, suggesting that trait allometry does not govern trait evolution on islands. Next (Chapter 3), I asked whether plants obey the infamous island rule, a putative trend in island evolution wherein small animals become large on islands and large animals become small. I demonstrate that plant stature and leaf area obey the island rule, and seed size does not. My findings illustrate that the island rule is more pervasive than previously considered, but that support for its predictions vary among plant functional traits. Third (Chapter 4), I demonstrate that the island rule results from evolutionary drift along bounded trait domains. The island rule has long been hypothesized to result from a suite of selective pressures. Applying my model to island plants, I show that evolutionary drift is the most parsimonious explanation for the island rule pattern. Finally (Chapter 5), to explore insular patterns in leaf size evolution, I conducted a large-scale, macroevolutionary analysis of leaf size on 98 of New Zealand’s offshore islands. Leaf gigantism was emblematic of island populations, and was most prominent in taxa with variable leaf morphologies on the mainland. Further, leaf gigantism was greatest in populations inhabiting old, distant islands, suggesting that time since divergence is a direct predictor of morphological differentiation between mainland and island populations. Overall, this thesis reveals novel patterns, and helps disentangle the distinct roles of natural selection and drift, in the evolution of plant form and function on islands. Finally, this thesis illustrates how investigating the changes in plant traits can help identify the evolutionary mechanisms operating on islands.

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Repeated patterns in the evolution of size in island plants

10.26686/wgtn.17151437.v1 ◽

2021 ◽

Author(s):

◽

Matthew Biddick

Keyword(s):

Functional Traits ◽

Large Scale ◽

Plant Traits ◽

Leaf Size ◽

Plant Functional Traits ◽

Common Element ◽

Island Rule ◽

Island Populations ◽

Stem Size ◽

Island Evolution

For reasons not fully understood, animals often evolve predictably on islands. For example, radiations of large, flightless birds are a common element of many island biotas. However, our understanding of how plants evolve on islands is comparatively poor. Further, an investigation into the evolution of island plants could help resolve unanswered questions about island animals. This thesis investigates insular size changes in a range of plant functional traits. First (Chapter 2), I explored size changes in 9 species of vines that have colonized islands from the New Zealand and Australian mainland. I asked whether leaf–stem allometry prohibits leaves and stems from evolving independently from one another. Island populations consistently produced larger leaves than did mainland populations. Moreover, changes in leaf size were not associated with concomitant changes in stem size, suggesting that trait allometry does not govern trait evolution on islands. Next (Chapter 3), I asked whether plants obey the infamous island rule, a putative trend in island evolution wherein small animals become large on islands and large animals become small. I demonstrate that plant stature and leaf area obey the island rule, and seed size does not. My findings illustrate that the island rule is more pervasive than previously considered, but that support for its predictions vary among plant functional traits. Third (Chapter 4), I demonstrate that the island rule results from evolutionary drift along bounded trait domains. The island rule has long been hypothesized to result from a suite of selective pressures. Applying my model to island plants, I show that evolutionary drift is the most parsimonious explanation for the island rule pattern. Finally (Chapter 5), to explore insular patterns in leaf size evolution, I conducted a large-scale, macroevolutionary analysis of leaf size on 98 of New Zealand’s offshore islands. Leaf gigantism was emblematic of island populations, and was most prominent in taxa with variable leaf morphologies on the mainland. Further, leaf gigantism was greatest in populations inhabiting old, distant islands, suggesting that time since divergence is a direct predictor of morphological differentiation between mainland and island populations. Overall, this thesis reveals novel patterns, and helps disentangle the distinct roles of natural selection and drift, in the evolution of plant form and function on islands. Finally, this thesis illustrates how investigating the changes in plant traits can help identify the evolutionary mechanisms operating on islands.

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Vertical stratification and effect of petiole and dry leaf size on arthropod feeding guilds in Cecropia pachystachya(Urticaceae)

Brazilian Journal of Biology ◽

10.1590/1519-6984.15213 ◽

2015 ◽

Vol 75 (3) ◽

pp. 517-523 ◽

Cited By ~ 1

Author(s):

SMA Novais ◽

AS Alvarenga ◽

LAD Falcão ◽

FS Neves

Keyword(s):

Structural Complexity ◽

Leaf Size ◽

Vertical Stratification ◽

Feeding Guilds ◽

Insect Herbivores ◽

Climate Variations ◽

Petiole Length ◽

Nesting Sites ◽

Free Feeding ◽

Species Richness And Abundance

AbstractThis study aimed to test for vertical stratification and the effects of dry leaf size on herbivore and predator arthropods and petiole length on insect borers in Cecropia pachystachya. The leaves were sampled in three strata: attached to the plant, suspended on the vegetation and on the ground. We detected vertical stratification only in the guild of predator arthropods associated with dry leaves, with lower richness and abundance in the attached stratum. In addition, larger leaves positively affected the insect herbivore fauna, whereas the richness and abundance of insect borers increased with petiole length. The greater isolation of leaves attached to trees relative to the surrounding vegetation likely creates greater difficulty for dispersal and colonization by non-winged predators such as spiders. Larger dry leaves provide more shelter against predators and climate variations for insect herbivores. Moreover, larger petioles increase the availability of resources and nesting sites for insect borers. These results are consistent with other studies that found a similarity in the structure of feeding guilds across vertical strata and with studies that showed an increase in species richness and abundance of free-feeding insect herbivores with increasing structural complexity of their host.

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Sweet Potato Canopy Morphology: Leaf Distribution

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.115.1.39 ◽

1990 ◽

Vol 115 (1) ◽

pp. 39-45 ◽

Cited By ~ 5

Author(s):

Zana C. Somda ◽

Stanley J. Kays

Keyword(s):

Leaf Area ◽

Sweet Potato ◽

Ipomoea Batatas ◽

Plant Density ◽

Leaf Size ◽

Progressive Increase ◽

Leaf Number ◽

Petiole Length ◽

Plant Densities ◽

Leaf Distribution

Changes in leaf distribution of the sweet potato [Ipomoea batatas (L.) Lam.] cultivar Jewel were assessed bi-weekly for 18 weeks at three plant densities (15, 30, and 45 cm × 96-cm spacing). The distribution of leaves on the branches and the timing at which leaf number stabilized were affected by the plant density. Plant density resulted in significant differences in the number of leaves and percentage of missing leaves during the growing season. Leaf number and total leaf area varied substantially in response to plant density, but individual lamina and petiole lengths and leaf area did not vary. Average petiole and leaf lengths and leaf size increased during the season, with the maximum length and area dependent on the type of branch on which the leaf was formed. Average petiole length per branch and the susceptibility to leaf loss increased with descending branch hierarchy (secondary branch < primary branch < main stem). Leaf losses after the 4th week tended to parallel a progressive increase in petiole length of new leaves, suggesting shading as a primary cause of leaf shedding and the loss of the oldest leaves first.

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Variation in waterlogging response among ecotypes of Trifolium subterraneum ssp. yanninicum and their relationships with site of origin

10.21203/rs.3.rs-896192/v1 ◽

2021 ◽

Author(s):

Gereltsetseg Enkhbat ◽

Megan H. Ryan ◽

Phillip G. H. Nichols ◽

Kevin J. Foster ◽

Yoshiaki Inukai ◽

...

Keyword(s):

Leaf Size ◽

Trifolium Subterraneum ◽

Dry Weight ◽

Phenotypic Traits ◽

Petiole Length ◽

Waterlogging Tolerance ◽

Seedling Traits ◽

Shoot Dry Weight ◽

Summer Temperatures ◽

Length Reduction

Abstract Background and AimsIn the annual pasture legume Trifolium subterraneum, ssp. yanninicum exhibits higher waterlogging tolerance than ssp. brachycalycinum and ssp. subterraneum. This study investigates waterlogging tolerance within ssp. yanninicum ecotypes and explores correlations with seedling phenotypic traits and site of origin eco-geographic variables.MethodsTwenty eight diverse ssp. yanninicum ecotypes collected from the Mediterranean region and four cultivars were grown in a controlled environment glasshouse. After 14 days of growth seedling traits were measured. After 21 days of growth, free-drained (control) and waterlogged treatments were imposed for 28 days. Eco-geographic variables were generated from ‘WorldClim’ using collection site locations.ResultsUnder waterlogging, shoot relative growth rate (RGR) ranged from 87–108% and root RGR ranged from 80–116% of controls. Waterlogging reduced shoot dry weight (DW) in four of 32 genotypes, while root DW was reduced in 13 genotypes. Leaf size was maintained, or even increased, under waterlogging in 31 genotypes. However, petiole length was more affected by waterlogging and has value as a waterlogging tolerance indicator. Waterlogging tolerance was not significantly correlated with seedling DW, flowering time or precipitation at the site of origin, while shoot growth under waterlogging had a positive correlation with summer temperatures at origin.ConclusionsGenotypes of ssp. yanninicum tolerated transient waterlogging and greater tolerance was observed among ecotypes, rather than cultivars. An easy-to-measure indicator of tolerance was found in petiole length reduction. This study highlights untapped genotypic variability for breeders to improve the productivity and persistence of ssp. yanninicum under waterlogging.

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Plants obey (and disobey) the island rule

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1907424116 ◽

2019 ◽

Vol 116 (36) ◽

pp. 17632-17634 ◽

Cited By ~ 9

Author(s):

M. Biddick ◽

A. Hendriks ◽

K. C. Burns

Keyword(s):

Leaf Area ◽

Seed Size ◽

Functional Traits ◽

Small Animals ◽

Island Rule ◽

Southwest Pacific ◽

Plant Stature ◽

Large Animals

The island rule predicts that small animals evolve to become larger on islands, while large animals evolve to become smaller. It has been studied for over half a century, and its validity is fiercely debated. Here, we provide a perspective on the debate by conducting a test of the island rule in plants. Results from an extensive dataset on islands in the southwest Pacific illustrate that plant stature and leaf area obey the island rule, but seed size does not. Our results indicate that the island rule may be more pervasive than previously thought and that support for its predictions varies among functional traits.

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Patterns of flammability of the California oaks: the role of leaf traits

Canadian Journal of Forest Research ◽

10.1139/x2012-138 ◽

2012 ◽

Vol 42 (11) ◽

pp. 1965-1975 ◽

Cited By ~ 54

Author(s):

Eamon A. Engber ◽

J. Morgan Varner

Keyword(s):

Plant Traits ◽

Fire Regime ◽

Fire Behavior ◽

Volume Ratio ◽

Leaf Size ◽

Fire Regimes ◽

Individual Species ◽

Individual Plant ◽

Leaf Margin ◽

Data Set

Fire is one of the most important processes driving plant community composition and structure. Fire regimes are largely governed by climate, vegetation structure, and individual plant traits that influence flammability. We assessed the mechanistic drivers of flammability for a diverse group of 18 California Quercus and allied Chrysolepis and Notholithocarpus species, addressing variation in leaf physical traits, growth form (tree or shrub), phylogeny (Quercus subgenera), and fire regime (low, mixed, or high severity). Differences in flammability were not strongly driven by leaf habit, leaf margin type, or surface area to volume ratio; simple measures of leaf size accounted for most of the observed variation. Further, leaf size was tightly linked to fuelbed depth, a known driver of fire behavior. Litter from trees was generally more flammable than litter from shrubs, primarily a function of differences in leaf size. A hierarchical clustering analysis on the flammability data set divided the oaks into three clusters of low, intermediate, and high flammability, corresponding closely to high-, mixed-, and low-severity fire regimes, respectively. The link between plant flammability traits and fire regime provides further evidence that individual species affect ecosystem processes.

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The diversity of leaves and asiaticoside content on three accessions of Centella asiatica with the addition of chicken manure fertilizer

Biodiversitas Journal of Biological Diversity ◽

10.13057/biodiv/d210325 ◽

2020 ◽

Vol 21 (3) ◽

Author(s):

Happy Maratul ◽

YULI WIDYASTUTI ◽

SUPRIYONO ◽

Ahmad Yunus

Keyword(s):

Leaf Morphology ◽

Centella Asiatica ◽

Leaf Size ◽

Chicken Manure ◽

Leaf Width ◽

Petiole Length ◽

Randomized Design ◽

Completely Randomized Design ◽

Chloroform Methanol ◽

Observation Results

Abstract. Mumtazah HM, Supriyono, Widyastuti Y, Yunus A. 2020. The diversity of leaves and asiaticoside content on three accessions of Centella asiatica with the addition of chicken manure fertilizer. Biodiversitas 21: 1035-1040. Centella asiatica (L.) commonly known as an essential medicinal herb. This plant has high diversity, especially in leaf morphology. The main objective of this research was to determine the morphology of leaves and the effect of chicken manure dosage on the increase of asiaticoside content. The leaves of three accessions characterized, and then C. asiatica planted. The research design used a completely randomized design (CRD) factorial, with the first factor is accession (C) with 3 levels (C1: accession 1, C2: accession 2, C3: accession 3). The second factor was chicken manure with 4 levels dosage (P1: 0 ton ha-1, P2: 10 tons ha-1, P3: 15 tons ha-1 and P4: 20 tons ha-1). Asiaticoside analysis used the TLC method with chloroform: methanol: water (65:25:4) as mobile phase. The result from this research showed that the diversity in leaf morphology of three accessions is in leaf size and petiole length. Accession 3 has the widest leaf size (7.3 cm) and the longest petiole (9.8 cm), accession 2 with a leaf width of 5.8 cm and petiole length in 8.5 cm, while the accession 1 has the least leaf width (5.3 cm) and the length of the petiole is the shortest with 7.3 cm. Observation results of asiaticoside showed that the highest content of asiaticoside produced by accession 3 (0.19%), then accession 1 with a content of 0.15%, while accession 2 showed the lowest asiaticoside content (0.13%). The treatment of chicken manure addition significantly increase asiaticoside content in accessions 1 and 3, but in accession 2 it was not significantly increased. The highest content of asiaticoside (0.34%) were in accession 3 with the addition of chicken manure 20 tons ha-1 (P4).

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