Exploring Evolution at Pismo State Beach
© Bob Field
2006-07-11
Explore the natural
beauty of the lagoon, gardens, dunes, and beach. Discover the unity and
diversity of life and the powers of the sea, sky, and land. Discuss seasonal
changes and tides. Rain cancels. Meet at Nature Center in Oceano Campground. (*M) 2 miles in 2 hours
Introduction
The topic is the physical and biological evolution of everything you can
see around Pismo State Beach. The theme is that everything you see from the
Pismo State Beach has a natural history; that is, everything changes over time.
The Pismo State Beach is a special place because of its
intrinsic beauty, the result of the meeting of sea, sky, and land. We will walk
a half mile along the lagoon, pass through the garden, explore the dunes, and
stop at the beach. We will examine marine terraces, powerful crashing waves,
the light and color of the sky, and explore the interactions and relationships
among the five kingdoms of life – plant, animal, algae, fungus, and bacteria.
There is much to talk about and each walk may emphasize different factors depending
on the season and the visitors’ interests.
At each stop, we
will discuss things we saw that were influenced by the ocean, directly or
indirectly, or by the Sun, atmosphere, or solid Earth. Our local natural
history illustrates how evolutionary processes work. The idea is to start with
the concrete – what you actually see – and go to the abstract – what you don’t
see. We will meet outside the Nature Center at the Oceano Campground on Pier
Avenue. We will stop at the wood railing to enjoy the scenic wonders of the
lagoon and to examine the relationships between the plants and animals that you
see. We will stop on the concrete pad with the metal railing and look for ducks
up close. We will stop at the poison oak sign briefly and discuss why plants
manufacture toxins. Then we will look for turtles and birds on a raft and walk
to the end of the paved part of the lagoon trail. When we enter the garden, we
will look for more examples of the five k
ingdoms of life.
After we pass the amphitheater and before the Grand Dune
Trail sign, we will make a short excursion to the top of a dune on an unmarked
trail. Weather permitting, this panorama provides a close up view of the dunes,
a clear view of the sky and vistas of the ocean and rugged marine terraces in
the distance. We will return to the mid-ramp road, and if time permits, we will
walk to the beach for a closer view of the ocean and a discussion of life on
the beach and in the ocean. From here visitors can enjoy the beach on their own
or return to the Nature Center, which is 15 minutes away. An optional picnic
lunch could precede a visit to the Nature Center to discuss the specimens of
local birds, mammals, and aquatic and terrestrial invertebrates that are on
display.
Subthemes and transitions
1. Co-evolution, cooperation, competition, and reproductive
strategies are all factors in the ecosystem that includes all five living
kingdoms. Changing conditions and radiation into new environments favored
descendants with certain traits acquired by means of natural selection. Off our
coast, there are peat beds, precursors to coal, typically formed from
undecomposed woody plants that evolved before any decomposers could break down
their strong carbon-based fibers. The junipers and other conifers are trees
that do not flower and are related to plants that evolved 300 million years
ago, unlike most trees that evolved from flowering plants perhaps 150 million
years ago. Did different types of trees evolve from different plants rather
than from a common ancestor tree?
2. Flowering plants evolved from algae with help from
bacteria (fixing nitrogen), fungi (phosphorus and minerals from the soil), and
animals (insect, bird, or bat pollinators). Many plants also rely on animals to
spread seeds which are often contained in fruits that attract animals. Plants
and animals rely on microbes in many ways that we barely realize. Microbes have
altered the Earth’s surface in many ways for nearly four billion years. One of
the forces of nature is the lichen that grows on rocks and trees, whose acids
help break down rock and form soil. Did you know that lichens are a symbiotic
combination of a decomposer (fungus) and a producer (either algae or
cyanobacteria or both)?
3. Chance mutations
of DNA enabled some descendants of green algae to evolve into multicellular,
differentiated, vascular plants with the ability to form leaves and to form and
disperse seeds through the production of flowers and fruits. In addition to
flowers and fruits, plants often produce substances that attract or repel animals
including fragrances, flavors, 
and toxins. Many
other organisms including single celled microbes produce toxins as well. The
ability to absorb, reflect, or scatter light and color also influences the
survivability of organisms encompassing photosynthesis (light collection for
energy), sensing light sources and images (light collection for information),
and alterations in an organism’s visibility (camouflage, warning colors,
attractive displays). If you visit the Monarch Butterfly Grove in late fall or
early winter, you can learn more about the influences of substances as diverse
as toxins and pigments.
4. Where did the water in the bay come from? Where else do
you find water? How does water interact with sunlight and with the heat
radiated from the Earth’s surface? The Sun influences the ocean, the
atmosphere, and the land in many ways; it is the energy source for winds,
waves, tides, air and water temperature, and the web of life. Over billions of
years, changes in the Sun’s output can be extremely important.
5. Imagine air, water, rocks, bones, plants, and animals.
What are they made out of? Which one has the smallest fraction of oxygen atoms?
Composition influences structure, but structure determines function. The
atmosphere influences the ocean and the land and yet life itself has altered
the atmosphere and has affected climate and living conditions and the course of
evolution. Over billions of years, changes in the composition of the atmosphere
have proven disastrous for some forms of life and beneficial to others. Where
would you find the greatest mass of life? Where is the greatest diversity of
life?
6. The structure, composition, origin, and evolution of the
sedimentary rocks and sand that you can see from the beach reveal the forces of
nature that have deposited and then altered them, the ocean being one of the
key influences. Morro Rock and the other volcanic peaks in our county have a
different history than the sloping hills of sedimentary rocks in the distance
and the sandy beaches and dunes near us. The tops of continents rise above sea
level because their light colored and light-weight silica-rich rocks lost much
of their heavy metals like iron and magnesium when they were molten. Elements
like calcium, silicon, and aluminum originally came from the erosion of
continental igneous rock that came from the depths of the Earth. Some minerals
found in sedimentary rocks cycled through algae known as diatoms and other
microorganisms that extract silica from seawater. The structure, composition,
origin, and evolution of sand, mud, and rocks reveal the forces of nature that
have deposited and then altered them, the ocean being one of the key
influences.
7. Organisms rely on solar and/or geothermal energy sources
and fluids and nutrients from the air, water, and land. The appearance and
behavior of plants and animals are adaptations to daily and seasonal changes in
the environment including tides and weather that evolved over millions of years
by means of natural selection.
8. Visitor options: The appearance and behavior of plants
and animals vary with daily and seasonal changes in the environment including
tides and weather as a result of natural selection. The Nature Center has some
fine exhibits featuring local birds, mammals, and aquatic and terrestrial
invertebrates as well as other information about the local natural history. For
more information on my Global Evolution Education Project, see GEEP or return to my home page.
Discussion
questions about natural systems
The natural history of planet Earth is the result of the
interactions of eight natural systems: oceans, atmosphere, solid Earth, Sun,
molecules, cells, organisms, and ecosystems. These eight guiding questions are
common to all of our informal science education programs:
1.
What do you see
(observations and descriptions)?
2.
What are natural
systems made out of (composition and structure)?
3.
How do natural systems
work (material properties and interactions with energy)?
4.
How do natural systems
change over time (evolutionary processes)?
5.
Where do natural
systems come from (origin and/or formation from building blocks)?
6.
What are the
relationships between the parts of a system (interactions and/or common
origins)?
7.
What are the
relationships between natural systems (interactions and/or common origins)?
8.
How do natural systems
become more complex over time (entropy decreases)?
Conclusions
Everything
evolves; everything changes over time - the sea, sky, land, and life itself.
Everything
you see is highly interactive and literally closely related.
It is the
role of science to provide plausible natural explanations for natural
phenomena.
How do
things change? When energy flows, complexity grows.