The economy of reproduction in dimorphic ferns

Britton, Michael R.; Watkins, James E.

doi:10.1093/aob/mcw177

Cited by 15 publications

(14 citation statements)

References 43 publications

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“…This has been shown for many seed plant taxa where flowering and fruiting structures can contribute directly to net carbon gain (reviewed in Raven and Griffiths 2015 ). In some ferns, however, the production of fertile fronds in monomorphic species comes at considerable costs and has long-term consequences for future reproduction ( Britton and Watkins 2016 ; Watkins et al 2016 ). Nothing is known of the photosynthetic capacity of microphylls and megaphylls in cycad strobili, yet most are green during early stages of development.…”

Section: Discussionmentioning

confidence: 99%

Sex-specific differences in functional traits and resource acquisition in five cycad species

et al. 2017

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The Mesozoic is often referred to as the “age of Cycads.” During this period, dinosaurs roamed vast Cycad forests, yet modern Cycads are a vestige of their Mesozoic glory. Extant species represent the oldest lineage of dioecious seed-bearing plants. This curious phylogenic position is matched by their unusual ecology: most species are extremely rare while others form dense colonies that may play important roles in forest function. In spite of this and quite remarkably, Cycads are the most poorly studied lineage of seed plants and almost nothing is known of their ecophysiology. The study by Krieg et al. is the first of its kind to examine sex-mediated ecophysiology in Cycads. Their results show unexpended differences in photosynthetic physiology and highlight the role that nitrogen fixing soil bacteria may play in Cycad reproduction and ecology. They found that species can vary markedly in nitrogen relations and that plant sex can drive unique leaf physiology. Their study is a cycadological call to arms for plant scientists to refocus efforts on this enigmatic group.

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Section: Discussionmentioning

confidence: 99%

Sex-specific differences in functional traits and resource acquisition in five cycad species

et al. 2017

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“…Fossil O. sensibilis is essentially indistinguishable from the living species (Rothwell and Stockey, 1991), as is fossil Ginkgo (Brown, 1962). O. sensibilis exhibits among the highest investment in belowground biomass observed among extant ferns (Britton and Watkins, 2016), and these rhizomes can survive temperatures higher than −17.5°C (Sato, 1982). Ginkgo similarly produces hysteresis (antifreeze) proteins (Duman and Olsen, 1993) and rhizome-like basal chichi, which have already been implicated in the survival of this taxon across the K/Pg boundary (Tredici, 1992), so the survival of these more temperate taxa with recalcitrant disseminules is not unexpected.…”

Section: Discussionmentioning

confidence: 94%

Seed traits linked to differential survival of plants during the Cretaceous/Paleogene impact winter

Berry¹

2020

Acta Palaeobotanica

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In past investigations the pattern of differential survival of plants across the K/Pg boundary has been viewed as incompatible with severe asteroid impact winter scenarios (i.e., an impact winter lasting more than a few months), particularly the enigmatic survival of coryphoid palms and Pandanus (screw pine). Stateof- the-art climate models based on soot, sulfate and nano-sized dust aerosols predict a global impact winter that drastically reduced precipitation and resulted in a transient period of total darkness and permafrost conditions. This suggests that the plants most likely to have been affected by the global mass-extinction event were tropical phanerophytes that produce recalcitrant seeds, which by definition are desiccation-intolerant, survive less than a year, and cannot survive freezing. However, this hypothesis has never been tested. In this study I sampled over 100 plant species from the global fossil record that have a high probability of having produced either recalcitrant seeds/disseminules (n1 = 58) or orthodox seeds (n2 = 59), based on their phylogenetic relationships with extant taxa that either are monomorphic for these traits or specifically exhibit a genetic marker for abscisic acid inhibition associated with seed dormancy and recalcitrance. A one-tailed z-test for the difference between two proportions revealed that plant taxa with a high probability of having produced recalcitrant seeds had significantly lower survivorship than plant taxa with a high probability of having produced orthodox seeds (p < 0.0001). Based on these data, it can be concluded that plants which formed a frost-tolerant seed bank during the latest Maastrichtian were significantly more likely to survive the K/Pg impact winter than plants which did not (including palms). These data clearly indicate that the K/Pg impact winter probably lasted longer than a year and that it selected for seed-based traits that effectively sorted correlated functional traits of mature plants (i.e., leaf physiognomic features). This novel hypothesis stands as an alternative to J.A. Wolfe’s classic hypothesis that a mild K/Pg impact winter selected for fast-growing angiosperms with deciduous leaves and did not affect the plant communities of the Southern Hemisphere. Potential mechanisms for the rare survival of tropical, recalcitrant-seeded plants are discussed.

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“…3A, B ) which may be critical to reaching the carbon and NSC threshold required to produce reproductive structures and leaves during reproductive phases. However, Zamia species can have large underground storage organs ( Whitelock, 2002 ) and studies in other plant groups, like ferns, have shown that leaf production is achieved by expending carbon that was fixed and stored in prior years ( Britton and Watkins Jr, 2016 ). The time course and translocation of carbohydrates and other nutrients is not well understood in cycads ( Gosetti et al, 2022 ).…”

Section: Discussionmentioning

confidence: 99%

“…In some seed-free species that exhibit fertile-sterile leaf dimorphy, fertile leaves have been shown to be net carbon sinks with net carbon losses via respiration ( Britton and Watkins Jr, 2016 ), suggesting that specialized reproductive tissues may require increased plant photosynthesis to compensate. Moreover, studies in other dioecious seed plant groups have measured physiological differences between sexes ( Gehring and Monson, 1994 ), with ovulate plants presumed to incur higher reproductive costs and often exhibiting increased photosynthetic carbon gain capacity ( Obeso et al, 1998 ; Nicotra, 1999 ; Groen et al, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Reproductive phases coincide with changes in morphology and photosynthetic physiology in an endangered cycad species

Krieg¹,

Gosetti²,

Watkins

et al. 2023

Conservation Physiology

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Cycadales is highly endangered and one of the oldest dioecious gymnosperm lineages, making their reproductive biology highly relevant to conservation efforts and our understanding of the impact of dioecy, yet cycad reproductive ecophysiology is poorly understood. We examined how the costs associated with reproduction may impact basic physiological variation in cycad species. Specifically, we measured traits related to functional morphology and photosynthetic physiology in sterile and fertile staminate plants (‘males’) of Zamia portoricensis. Light response curves showed that sterile plants had greater light-use efficiency and maximum photosynthetic capacity per area compared with fertile plants. However, fertile and sterile plants exhibited similar respiration rates. We found significantly more nitrogen in leaves of fertile individuals, but similar nitrogen isotope composition and no differences in carbon content between sterile and fertile individuals. Despite having lower leaf-level photosynthetic rates, fertile plants had greater canopy-level photosynthesis than sterile plants, which was achieved by increasing leaf number and total leaf area. Our data suggest that sterile individuals may have greater light demands relative to fertile individuals, and fertile individuals may have greater nitrogen demands, which may be critical for successful reproductive events in staminate plants of the endangered cycad, Z. portoricensis.

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The economy of reproduction in dimorphic ferns

Cited by 15 publications

References 43 publications

Sex-specific differences in functional traits and resource acquisition in five cycad species

Sex-specific differences in functional traits and resource acquisition in five cycad species

Seed traits linked to differential survival of plants during the Cretaceous/Paleogene impact winter

Reproductive phases coincide with changes in morphology and photosynthetic physiology in an endangered cycad species

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