Leaf heteroblasty in eucalypts: biogeographic evidence of ecological function

Vlasveld, Carolyn; O'Leary, Benjamin A.; Udovicic, Frank; Burd, Martin

doi:10.1071/bt17134

Cited by 13 publications

(8 citation statements)

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“…A generally similar conclusion was reached in a comparison of juvenile and adult leaves of Eucalyptus globulus (Vlasveld et al. ). Thus the longer retention of juvenile foliage in the species from areas where initial interspecific competition is likely to be high in the early growth stages is adaptive for such areas.…”

Section: Discussionsupporting

confidence: 80%

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

2019

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The foliar shift from juvenile needle leaves to the mature scale leaves was investigated in five Callitris species. Their habitats range from rainforest to the semi‐arid. In C. macleayana from the most mesic environment the change from needle to scale leaves is variable and juvenile leave are even retained on mature trees. In the other four species there is a rapid change in size and structure to scale leaves. Anatomically the photosynthetic tissue is condensed and stomatal area is limited compared to species with conventional leaves. A hypodermis is most prominent on the abaxial side of the leaves and may play a role in protection from high solar radiation as most species grow in high light areas. While stomata in the four taxa from wet or moderate rainfall areas are freely exposed, those of C. gracilis from semi‐arid habitats are well protected in longitudinal furrows between the decurrent leaves. The reduced leaf area of all species allows close association between the water‐conducting xylem and the stomata that will facilitate rapid leaf conductance. This links with the anisohydric physiology of the genus and the shallow rooting that can take advantage of brief rainfall events for species in arid climates.

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Section: Discussionsupporting

confidence: 80%

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

2019

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“…host trees compared to trees of Eucalyptus spp. and other genera, given the morphological similarities between trees of the Corymbia and Eucalyptus genera (Vlasveld et al, 2018); further investigation revealed a higher ratio of female koalas in Corymbia host trees. This may explain a portion of the decreased detectability of animals in these trees as smaller female koalas were found to be more difficult to detect.…”

Section: Discussionmentioning

confidence: 86%

Evaluating new technology for biodiversity monitoring: Are drone surveys biased?

Corcoran

Denman

Hamilton

2021

Ecology and Evolution

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Drones and machine learning‐based automated detection methods are being used by ecologists to conduct wildlife surveys with increasing frequency. When traditional survey methods have been evaluated, a range of factors have been found to influence detection probabilities, including individual differences among conspecific animals, which can thus introduce biases into survey counts. There has been no such evaluation of drone‐based surveys using automated detection in a natural setting. This is important to establish since any biases in counts made using these methods will need to be accounted for, to provide accurate data and improve decision‐making for threatened species. In this study, a rare opportunity to survey a ground‐truthed, individually marked population of 48 koalas in their natural habitat allowed for direct comparison of the factors impacting detection probability in both ground observation and drone surveys with manual and automated detection. We found that sex and host tree preferences impacted detection in ground surveys and in manual analysis of drone imagery with female koalas likely to be under‐represented, and koalas higher in taller trees detected less frequently when present. Tree species composition of a forest stand also impacted on detections. In contrast, none of these factors impacted on automated detection. This suggests that the combination of drone‐captured imagery and machine learning does not suffer from the same biases that affect conventional ground surveys. This provides further evidence that drones and machine learning are promising tools for gathering reliable detection data to better inform the management of threatened populations.

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“…Indeed, of the four traits studied, vegetative juvenility would be the one most likely to reflect indirect selection involving unmeasured ("hidden") traits that could also influence seedling survival. While we assessed vegetative juvenility of the seedlings based on the node at which the first petiolate leaf was produced, this is potentially a surrogate for a wide range of physical, chemical and physiological changes that can occur, as documented in other eucalypt species (James and Bell, 2001;Borzak et al, 2015;Vlasveld et al, 2018;Lucani et al, 2019). It is therefore possible that the directional selection detected against vegetative juvenility in the mesic population could reflect indirect selection on a "hidden" (unmeasured) trait with a negative phenotypic correlation with vegetative juvenility.…”

Section: Discussionmentioning

confidence: 99%

Directional Selection on Tree Seedling Traits Driven by Experimental Drought Differs Between Mesic and Dry Populations

et al. 2021

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We evaluated population differences and drought-induced phenotypic selection on four seedling traits of the Australian forest tree Eucalyptus pauciflora using a glasshouse dry-down experiment. We compared dry and mesic populations and tested for directional selection on lamina length (reflecting leaf size), leaf shape, the node of ontogenetic transition to the petiolate leaf (reflecting the loss of vegetative juvenility), and lignotuber size (reflecting a recovery trait). On average, the dry population had smaller and broader leaves, greater retention of the juvenile leaf state and larger lignotubers than the mesic population, but the populations did not differ in seedling survival. While there was statistical support for directional selection acting on the focal traits in one or other population, and for differences between populations in selection gradient estimates for two traits, only one trait—lamina length—exhibited a pattern of directional selection consistent with the observed population differences being a result of past adaptation to reduce seedling susceptibility to acute drought. The observed directional selection for lamina length in the mesic population suggests that future increases in drought risk in the wild will shift the mean of the mesic population toward that of the dry population. Further, we provide evidence suggesting an early age trade-off between drought damage and recovery traits, with phenotypes which develop larger lignotubers early being more susceptible to drought death. Such trade-offs could have contributed to the absence of population mean differences in survival, despite marked differentiation in seedling traits.

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Leaf heteroblasty in eucalypts: biogeographic evidence of ecological function

Cited by 13 publications

References 50 publications

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

Evaluating new technology for biodiversity monitoring: Are drone surveys biased?

Directional Selection on Tree Seedling Traits Driven by Experimental Drought Differs Between Mesic and Dry Populations

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